diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5631f49584..563db5dd14 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -82,6 +82,8 @@ jobs:
           sudo /usr/bin/python -m pip install src/bcf
           sudo /usr/bin/python -m pip install pytest
           sudo /usr/bin/python -m pip install isodate
+          sudo /usr/bin/python -m pip install lark
+          sudo /usr/bin/python -m pip install networkx
 
       - name: Test
         run: |
diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index 15ff97f5b8..45c1edb163 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -62,6 +62,10 @@ endif()
 OPTION(USERSPACE_PYTHON_PREFIX "Installs IfcPython for the current user only instead of system-wide." OFF)
 OPTION(ADD_COMMIT_SHA "Add commit sha and branch in version number, warning results in many rebuilds, requires git" OFF)
 
+IF(NOT CMAKE_BUILD_TYPE)
+	SET(CMAKE_BUILD_TYPE "Release")
+ENDIF()
+
 # TODO QtViewer is deprecated ATM as it uses the 0.4 API
 # OPTION(BUILD_QTVIEWER "Build IfcOpenShell Qt GUI Viewer (requires Qt 4 framework)." OFF)
 include(GNUInstallDirs)
@@ -478,10 +482,6 @@ if(HDF5_SUPPORT)
 	set(SWIG_DEFINES ${SWIG_DEFINES} -DWITH_HDF5)
 endif()
 
-IF(NOT CMAKE_BUILD_TYPE)
-	SET(CMAKE_BUILD_TYPE "Release")
-ENDIF()
-
 if(ENABLE_BUILD_OPTIMIZATIONS)
 	if(MSVC)
         # NOTE: RelWithDebInfo and Release use O2 (= /Ox /Gl /Gy/ = Og /Oi /Ot /Oy /Ob2 /Gs /GF /Gy) by default,
diff --git a/src/blenderbim/Makefile b/src/blenderbim/Makefile
index af7caa2423..a18b59d45e 100644
--- a/src/blenderbim/Makefile
+++ b/src/blenderbim/Makefile
@@ -46,8 +46,7 @@ BOOST_URL:=https://anaconda.org/conda-forge/boost/1.74.0/download/linux-64/boost
 LXML_URL:=https://files.pythonhosted.org/packages/19/d9/a69c6aff5673554df48120565a14a50eaa41d29ae03b02faa0b023666318/lxml-4.6.3-cp39-cp39-manylinux2014_x86_64.whl
 endif
 ifeq ($(PYVERSION), py310)
-# https://github.com/humanoid-path-planner/hpp-fcl/issues/272
-HPPFCL_URL:=https://anaconda.org/conda-forge/hpp-fcl/1.7.5/download/linux-64/hpp-fcl-1.7.5-py39hbcdfc36_0.tar.bz2
+HPPFCL_URL:=https://anaconda.org/conda-forge/hpp-fcl/1.8.0/download/linux-64/hpp-fcl-1.8.0-py310hdaf7e41_1.tar.bz2
 EIGENPY_URL:=https://anaconda.org/conda-forge/eigenpy/2.6.11/download/linux-64/eigenpy-2.6.11-py310hf3e5c9c_0.tar.bz2
 BOOST_URL:=https://anaconda.org/conda-forge/boost/1.74.0/download/linux-64/boost-1.74.0-py310h7c3ba0c_5.tar.bz2
 LXML_URL:=https://files.pythonhosted.org/packages/25/1e/19b46d8e8881fe0df2e20945d51919eeb1817836d62a90efa8506530e45c/lxml-4.8.0-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.manylinux_2_24_x86_64.whl
@@ -71,8 +70,7 @@ BOOST_URL:=https://anaconda.org/conda-forge/boost/1.74.0/download/osx-64/boost-1
 LXML_URL:=https://files.pythonhosted.org/packages/b8/74/a71f7ad72e8db54ce899efab84507b801660750cbbfa6a39e6717557d36a/lxml-4.6.3-cp39-cp39-macosx_10_9_x86_64.whl
 endif
 ifeq ($(PYVERSION), py310)
-# https://github.com/humanoid-path-planner/hpp-fcl/issues/272
-HPPFCL_URL:=https://anaconda.org/conda-forge/hpp-fcl/1.7.5/download/osx-64/hpp-fcl-1.7.5-py39h1e32b98_0.tar.bz2
+HPPFCL_URL:=https://anaconda.org/conda-forge/hpp-fcl/1.8.0/download/osx-64/hpp-fcl-1.8.0-py310h651ac30_1.tar.bz2
 EIGENPY_URL:=https://anaconda.org/conda-forge/eigenpy/2.6.11/download/osx-64/eigenpy-2.6.11-py310hc03097c_0.tar.bz2
 BOOST_URL:=https://anaconda.org/conda-forge/boost/1.74.0/download/osx-64/boost-1.74.0-py310h509978a_5.tar.bz2
 LXML_URL:=https://files.pythonhosted.org/packages/a1/44/17b7dac7a18807d30e2fe10c3328c152808f5464565e230bfd0e77f178c6/lxml-4.8.0-cp310-cp310-macosx_10_15_x86_64.whl
@@ -96,8 +94,7 @@ BOOST_URL:=https://anaconda.org/conda-forge/boost/1.74.0/download/win-64/boost-1
 LXML_URL:=https://files.pythonhosted.org/packages/72/d4/426ecb8849c47c3e370c87aa0ac05d85768df917ffea27fcd6686a5e6495/lxml-4.6.3-cp39-cp39-win_amd64.whl
 endif
 ifeq ($(PYVERSION), py310)
-# https://github.com/humanoid-path-planner/hpp-fcl/issues/272
-HPPFCL_URL:=https://anaconda.org/conda-forge/hpp-fcl/1.7.5/download/win-64/hpp-fcl-1.7.5-py39h2e7c763_0.tar.bz2
+HPPFCL_URL:=https://anaconda.org/conda-forge/hpp-fcl/1.8.0/download/win-64/hpp-fcl-1.8.0-py310hc5a3c62_1.tar.bz2
 EIGENPY_URL:=https://anaconda.org/conda-forge/eigenpy/2.6.11/download/win-64/eigenpy-2.6.11-py310hbd43d28_0.tar.bz2
 BOOST_URL:=https://anaconda.org/conda-forge/boost/1.74.0/download/win-64/boost-1.74.0-py310hc781a3c_5.tar.bz2
 LXML_URL:=https://files.pythonhosted.org/packages/f6/71/65c80a4caa1617a4c6e8fe1500cebb179db96232e2f623bfe6a1f4294e39/lxml-4.8.0-cp310-cp310-win_amd64.whl
@@ -118,7 +115,7 @@ endif
 	cp -r blenderbim/* dist/blenderbim/
 
 	# Provides IfcOpenShell Python functionality
-	cd dist/working && wget https://s3.amazonaws.com/ifcopenshell-builds/ifcopenshell-python-$(PYNUMBER)-v0.7.0-883b8a5-$(PLATFORM)64.zip
+	cd dist/working && wget https://s3.amazonaws.com/ifcopenshell-builds/ifcopenshell-python-$(PYNUMBER)-v0.7.0-2985bba-$(PLATFORM)64.zip
 	cd dist/working && unzip ifcopenshell-python*
 	cp -r dist/working/ifcopenshell dist/blenderbim/libs/site/packages/
 
@@ -292,8 +289,6 @@ endif
 	rm -rf dist/working
 
 	# Required by IFCClash
-# https://github.com/humanoid-path-planner/hpp-fcl/issues/272
-ifneq ($(PYVERSION), py310)
 	mkdir dist/working
 	cd dist/working && wget $(HPPFCL_URL)
 	cd dist/working && tar -xf hpp-fcl*
@@ -385,8 +380,6 @@ ifeq ($(PLATFORM), win)
 	cp -r dist/working/Library/bin/*.dll dist/blenderbim/libs/site/packages/hppfcl/
 endif
 	rm -rf dist/working
-# https://github.com/humanoid-path-planner/hpp-fcl/issues/272
-endif
 
 	# Required by BIMTester
 	mkdir dist/working
diff --git a/src/blenderbim/blenderbim/bim/__init__.py b/src/blenderbim/blenderbim/bim/__init__.py
index 52c4900bea..da0194dcec 100644
--- a/src/blenderbim/blenderbim/bim/__init__.py
+++ b/src/blenderbim/blenderbim/bim/__init__.py
@@ -79,17 +79,18 @@ for name in modules.keys():
 
 
 classes = [
-    operator.OpenUri,
-    operator.SelectDataDir,
-    operator.SelectSchemaDir,
-    operator.SelectIfcFile,
-    operator.OpenUpstream,
+    operator.AddIfcFile,
     operator.BIM_OT_add_section_plane,
     operator.BIM_OT_remove_section_plane,
-    operator.ReloadIfcFile,
-    operator.AddIfcFile,
-    operator.RemoveIfcFile,
     operator.ConfigureVisibility,
+    operator.OpenUpstream,
+    operator.OpenUri,
+    operator.ReloadIfcFile,
+    operator.RemoveIfcFile,
+    operator.SelectDataDir,
+    operator.SelectIfcFile,
+    operator.SelectSchemaDir,
+    operator.SelectURIAttribute,
     prop.StrProperty,
     prop.ObjProperty,
     prop.Attribute,
diff --git a/src/blenderbim/blenderbim/bim/data/gantt/index.mustache b/src/blenderbim/blenderbim/bim/data/gantt/index.mustache
index 67c5179f05..e75c171e3b 100644
--- a/src/blenderbim/blenderbim/bim/data/gantt/index.mustache
+++ b/src/blenderbim/blenderbim/bim/data/gantt/index.mustache
@@ -38,7 +38,7 @@
 <script type="text/javascript">
 var g = new JSGantt.GanttChart(document.getElementById('GanttChartDIV'), 'day');
 g.setOptions({
-    vCaptionType: 'Complete',  // Set to Show Caption : None,Caption,Resource,Duration,Complete,
+    vCaptionType: 'Caption',  // Set to Show Caption : None,Caption,Resource,Duration,Complete,
     vQuarterColWidth: 36,
     vDateTaskDisplayFormat: 'day dd month yyyy', // Shown in tool tip box
     vDayMajorDateDisplayFormat: 'mon yyyy - Week ww',// Set format to dates in the "Major" header of the "Day" view
@@ -50,6 +50,8 @@ g.setOptions({
     vFormatArr: ['Day', 'Week', 'Month', 'Quarter'], // Even with setUseSingleCell using Hour format on such a large chart can cause issues in some browsers,
     vShowRes: false, // Disable the resource column.
     vShowComp: false, // Disable the completion column.
+    vShowDur: false, // Disable the duration column, because jsgantt doesn't calculate durations the way we want.
+    vAdditionalHeaders: {ifcduration: {title: 'Duration'}},
     vUseToolTip: false, // Disable tooltips.
     vTotalHeight: 900,
 });
diff --git a/src/blenderbim/blenderbim/bim/data/templates/symbols.svg b/src/blenderbim/blenderbim/bim/data/templates/symbols.svg
index b3209968e5..ea0e4b3630 100644
--- a/src/blenderbim/blenderbim/bim/data/templates/symbols.svg
+++ b/src/blenderbim/blenderbim/bim/data/templates/symbols.svg
@@ -5,6 +5,20 @@
     </g>
     <g id="door-tag">
         <circle cy="1.75" r="5" fill="white" stroke="black" style="stroke-width: 0.25;" />
-        <line x1="-5" y1="1.75" x2="5" y2="1.75" style="stroke:black; stroke-width: 0.25;" />
+        <line x1="-5" y1="1.75" x2="5" y2="1.75" style="stroke: black; stroke-width: 0.25;" />
+    </g>
+    <g id="elevation-arrow">
+        <path style="fill: black;" d="M -7.07106 0 0 -7.07106 7.07106 0" />
+    </g>
+    <g id="elevation-tag">
+        <circle r="5" fill="white" stroke="black" style="stroke-width: 0.25;" />
+        <line x1="-5" y1="0" x2="5" y2="0" style="stroke: black; stroke-width: 0.25;" />
+    </g>
+    <g id="section-arrow">
+        <path style="fill: black;" d="M -7.07106 0 0 -7.07106 7.07106 0" />
+    </g>
+    <g id="section-tag">
+        <circle r="5" fill="white" stroke="black" style="stroke-width: 0.25;" />
+        <line x1="-5" y1="0" x2="5" y2="0" style="stroke: black; stroke-width: 0.25;" />
     </g>
 </svg>
diff --git a/src/blenderbim/blenderbim/bim/export_ifc.py b/src/blenderbim/blenderbim/bim/export_ifc.py
index 39bc82df35..063c793c80 100644
--- a/src/blenderbim/blenderbim/bim/export_ifc.py
+++ b/src/blenderbim/blenderbim/bim/export_ifc.py
@@ -28,6 +28,7 @@ import ifcopenshell
 import ifcopenshell.api
 import ifcopenshell.util.placement
 import blenderbim.tool as tool
+import blenderbim.core.geometry
 import blenderbim.core.aggregate
 import blenderbim.core.spatial
 import blenderbim.core.style
@@ -47,7 +48,7 @@ class IfcExporter:
             self.sync_deletions()
             self.sync_all_objects()
             self.sync_edited_objects()
-        extension = self.ifc_export_settings.output_file.split(".")[-1]
+        extension = self.ifc_export_settings.output_file.split(".")[-1].lower()
         if extension == "ifczip":
             with tempfile.TemporaryDirectory() as unzipped_path:
                 filename, ext = os.path.splitext(os.path.basename(self.ifc_export_settings.output_file))
@@ -179,6 +180,7 @@ class IfcExporter:
             self.sync_object_placement(grid_obj)
             if grid_obj.matrix_world != obj.matrix_world:
                 bpy.ops.bim.update_representation(obj=obj.name)
+        tool.Geometry.record_object_position(obj)
 
     def get_application_name(self):
         return "BlenderBIM"
diff --git a/src/blenderbim/blenderbim/bim/handler.py b/src/blenderbim/blenderbim/bim/handler.py
index 16c924c24f..9f615158ab 100644
--- a/src/blenderbim/blenderbim/bim/handler.py
+++ b/src/blenderbim/blenderbim/bim/handler.py
@@ -26,9 +26,7 @@ from blenderbim.bim.module.drawing.prop import RasterStyleProperty
 from bpy.app.handlers import persistent
 from blenderbim.bim.ifc import IfcStore
 from blenderbim.bim.module.owner.prop import get_user_person, get_user_organisation
-from ifcopenshell.api.attribute.data import Data as AttributeData
 from ifcopenshell.api.material.data import Data as MaterialData
-from ifcopenshell.api.style.data import Data as StyleData
 from ifcopenshell.api.type.data import Data as TypeData
 
 
@@ -68,11 +66,10 @@ def name_callback(obj, data):
     if isinstance(obj, bpy.types.Material):
         if obj.BIMObjectProperties.ifc_definition_id:
             IfcStore.get_file().by_id(obj.BIMObjectProperties.ifc_definition_id).Name = obj.name
-            AttributeData.load(IfcStore.get_file(), obj.BIMObjectProperties.ifc_definition_id)
             MaterialData.load_materials()
         if obj.BIMMaterialProperties.ifc_style_id:
             IfcStore.get_file().by_id(obj.BIMMaterialProperties.ifc_style_id).Name = obj.name
-            StyleData.load(IfcStore.get_file(), obj.BIMMaterialProperties.ifc_style_id)
+        refresh_ui_data()
         return
 
     if not obj.BIMObjectProperties.ifc_definition_id or "/" not in obj.name:
@@ -96,7 +93,7 @@ def name_callback(obj, data):
     if element.is_a("IfcTypeProduct"):
         TypeData.purge()
     element.Name = "/".join(obj.name.split("/")[1:])
-    AttributeData.load(IfcStore.get_file(), obj.BIMObjectProperties.ifc_definition_id)
+    refresh_ui_data()
 
 
 def color_callback(obj, data):
diff --git a/src/blenderbim/blenderbim/bim/helper.py b/src/blenderbim/blenderbim/bim/helper.py
index 230022467b..f0dab98427 100644
--- a/src/blenderbim/blenderbim/bim/helper.py
+++ b/src/blenderbim/blenderbim/bim/helper.py
@@ -48,6 +48,9 @@ def draw_attribute(attribute, layout, copy_operator=None):
     if copy_operator:
         op = layout.operator(f"{copy_operator}", text="", icon="COPYDOWN")
         op.name = attribute.name
+    if attribute.is_uri:
+        op = layout.operator("bim.select_uri_attribute", text="", icon="FILE_FOLDER")
+        op.data_path = attribute.path_from_id("string_value")
 
 
 def import_attributes(ifc_class, props, data, callback=None):
@@ -78,6 +81,8 @@ def import_attribute(attribute, props, data, callback=None):
         props.remove(len(props) - 1)
     elif data_type == "string":
         new.string_value = "" if new.is_null else data[attribute.name()]
+        if attribute.type_of_attribute().declared_type().name() == "IfcURIReference":
+            new.is_uri = True
     elif data_type == "boolean":
         new.bool_value = False if new.is_null else data[attribute.name()]
     elif data_type == "integer":
diff --git a/src/blenderbim/blenderbim/bim/ifc.py b/src/blenderbim/blenderbim/bim/ifc.py
index a375d51529..f5be2ea01f 100644
--- a/src/blenderbim/blenderbim/bim/ifc.py
+++ b/src/blenderbim/blenderbim/bim/ifc.py
@@ -86,6 +86,7 @@ class IfcStore:
             ifc_hash = hashlib.md5(ifc_key.encode("utf-8")).hexdigest()
             IfcStore.cache_path = os.path.join(bpy.context.scene.BIMProperties.data_dir, "cache", f"{ifc_hash}.h5")
             cache_settings = ifcopenshell.geom.settings()
+            cache_settings.set(cache_settings.STRICT_TOLERANCE, True)
             try:
                 IfcStore.cache = ifcopenshell.geom.serializers.hdf5(IfcStore.cache_path, cache_settings)
             except:
diff --git a/src/blenderbim/blenderbim/bim/import_ifc.py b/src/blenderbim/blenderbim/bim/import_ifc.py
index 45a074fd0b..35d1a40e34 100644
--- a/src/blenderbim/blenderbim/bim/import_ifc.py
+++ b/src/blenderbim/blenderbim/bim/import_ifc.py
@@ -163,6 +163,7 @@ class IfcImporter:
         self.settings = ifcopenshell.geom.settings()
         self.settings.set_deflection_tolerance(self.ifc_import_settings.deflection_tolerance)
         self.settings.set_angular_tolerance(self.ifc_import_settings.angular_tolerance)
+        self.settings.set(self.settings.STRICT_TOLERANCE, True)
         self.settings_native = ifcopenshell.geom.settings()
         self.settings_native.set(self.settings_native.INCLUDE_CURVES, True)
         self.settings_2d = ifcopenshell.geom.settings()
@@ -283,11 +284,13 @@ class IfcImporter:
             if c.ContextIdentifier in ["Body", "Facetation"]
         ]
         # Ideally, all representations should be in a subcontext, but some BIM programs don't do this correctly
-        self.body_contexts.extend([
-            c.id()
-            for c in self.file.by_type("IfcGeometricRepresentationContext", include_subtypes=False)
-            if c.ContextType == "Model"
-        ])
+        self.body_contexts.extend(
+            [
+                c.id()
+                for c in self.file.by_type("IfcGeometricRepresentationContext", include_subtypes=False)
+                if c.ContextType == "Model"
+            ]
+        )
         if self.body_contexts:
             self.settings.set_context_ids(self.body_contexts)
         # Annotation is to accommodate broken Revit files
@@ -363,7 +366,7 @@ class IfcImporter:
 
     def is_native_swept_disk_solid(self, representations):
         for representation in representations:
-            items = representation["raw"].Items or [] # Be forgiving of invalid IFCs because Revit :(
+            items = representation["raw"].Items or []  # Be forgiving of invalid IFCs because Revit :(
             if len(items) == 1 and items[0].is_a("IfcSweptDiskSolid"):
                 return True
         return False
@@ -1295,10 +1298,7 @@ class IfcImporter:
             name = style.Name or str(style.id())
             blender_material = bpy.data.materials.new(name)
 
-        old_definition_id = blender_material.BIMObjectProperties.ifc_definition_id
-        if not old_definition_id:
-            self.link_element(style, blender_material)
-        blender_material.BIMObjectProperties.ifc_definition_id = old_definition_id
+        self.link_element(style, blender_material)
 
         blender_material.BIMMaterialProperties.ifc_style_id = style.id()
         self.material_creator.styles[style.id()] = blender_material
@@ -1352,12 +1352,12 @@ class IfcImporter:
         elif surface_style.ReflectanceMethod == "FLAT":
             blender_material.use_nodes = True
 
-            output = {n.type: n for n in self.settings["material"].node_tree.nodes}.get("OUTPUT_MATERIAL", None)
+            output = {n.type: n for n in blender_material.node_tree.nodes}.get("OUTPUT_MATERIAL", None)
             bsdf = blender_material.node_tree.nodes["Principled BSDF"]
 
             mix = blender_material.node_tree.nodes.new(type="ShaderNodeMixShader")
             mix.location = bsdf.location
-            blender_material.node_tree.links.new(lightpath.outputs[0], output.inputs["Surface"])
+            blender_material.node_tree.links.new(mix.outputs[0], output.inputs["Surface"])
 
             blender_material.node_tree.nodes.remove(bsdf)
 
@@ -1722,10 +1722,10 @@ class IfcImporter:
             ):
                 verts = [None] * len(geometry.verts)
                 for i in range(0, len(geometry.verts), 3):
-                    verts[i], verts[i+1], verts[i+2] = ifcopenshell.util.geolocation.enh2xyz(
+                    verts[i], verts[i + 1], verts[i + 2] = ifcopenshell.util.geolocation.enh2xyz(
                         geometry.verts[i],
-                        geometry.verts[i+1],
-                        geometry.verts[i+2],
+                        geometry.verts[i + 1],
+                        geometry.verts[i + 2],
                         float(props.blender_eastings) * self.unit_scale,
                         float(props.blender_northings) * self.unit_scale,
                         float(props.blender_orthogonal_height) * self.unit_scale,
diff --git a/src/blenderbim/blenderbim/bim/module/bimtester/prop.py b/src/blenderbim/blenderbim/bim/module/bimtester/prop.py
index e3b438423b..a2ce7dad0d 100644
--- a/src/blenderbim/blenderbim/bim/module/bimtester/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/bimtester/prop.py
@@ -19,7 +19,7 @@
 import os
 from pathlib import Path
 from blenderbim.bim.prop import StrProperty
-from blenderbim.bim.module.root.prop import getIfcClasses
+from blenderbim.bim.module.root.prop import get_ifc_classes
 from bpy.types import PropertyGroup
 from bpy.props import (
     PointerProperty,
@@ -33,14 +33,11 @@ from bpy.props import (
 )
 
 scenarios_enum = []
-classes_enum = []
 
 
 def purge():
     global scenarios_enum
-    global classes_enum
     scenarios_enum = []
-    classes_enum = []
 
 
 def getScenarios(self, context):
@@ -68,7 +65,7 @@ class BimTesterProperties(PropertyGroup):
     feature: StringProperty(default="", name="Feature / IDS", update=refreshScenarios)
     steps: StringProperty(default="", name="Custom Steps")
     ifc_file: StringProperty(default="", name="IFC File")
-    audit_ifc_class: EnumProperty(items=getIfcClasses, name="Audit Class")
+    audit_ifc_class: EnumProperty(items=get_ifc_classes, name="Audit Class")
     qa_reject_element_reason: StringProperty(name="Element Rejection Reason")
     scenario: EnumProperty(items=getScenarios, name="Scenario")
     should_load_from_memory: BoolProperty(default=False, name="Load from Memory")
diff --git a/src/blenderbim/blenderbim/bim/module/boundary/operator.py b/src/blenderbim/blenderbim/bim/module/boundary/operator.py
index 05e91aad9a..2aad9c1bc2 100644
--- a/src/blenderbim/blenderbim/bim/module/boundary/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/boundary/operator.py
@@ -44,6 +44,19 @@ class Loader:
         self.load_settings()
         self.load_importer()
 
+    def create_mesh(self, boundary):
+        # ConnectionGeometry is optional in IFC schema for some reasons.
+        if not boundary.ConnectionGeometry:
+            return None
+        surface = boundary.ConnectionGeometry.SurfaceOnRelatingElement
+        # workaround for unvalid geometry provided by Revit. See https://github.com/IfcOpenShell/IfcOpenShell/issues/635#issuecomment-770366838
+        if surface.is_a("IfcCurveBoundedPlane") and not getattr(surface, "InnerBoundaries", None):
+            surface.InnerBoundaries = ()
+        shape = ifcopenshell.geom.create_shape(self.settings, surface)
+        mesh = self.ifc_importer.create_mesh(None, shape)
+        self.ifc_importer.link_mesh(shape, mesh)
+        return mesh
+
     def load_settings(self):
         self.settings = ifcopenshell.geom.settings()
         self.settings.set(self.settings.EXCLUDE_SOLIDS_AND_SURFACES, False)
@@ -61,13 +74,7 @@ class Loader:
         obj = tool.Ifc.get_object(boundary)
         if obj:
             return obj
-        surface = boundary.ConnectionGeometry.SurfaceOnRelatingElement
-        # workaround for unvalid geometry provided by Revit. See https://github.com/IfcOpenShell/IfcOpenShell/issues/635#issuecomment-770366838
-        if surface.is_a("IfcCurveBoundedPlane") and not getattr(surface, "InnerBoundaries", None):
-            surface.InnerBoundaries = ()
-        shape = ifcopenshell.geom.create_shape(self.settings, surface)
-        mesh = self.ifc_importer.create_mesh(None, shape)
-        self.ifc_importer.link_mesh(shape, mesh)
+        mesh = self.create_mesh(boundary)
         obj = bpy.data.objects.new(f"{boundary.is_a()}/{boundary.Name}", mesh)
         obj.matrix_world = blender_space.matrix_world
         boundaries_collection = get_boundaries_collection(blender_space)
diff --git a/src/blenderbim/blenderbim/bim/module/document/__init__.py b/src/blenderbim/blenderbim/bim/module/document/__init__.py
index edfe7a60ef..93dbf703b2 100644
--- a/src/blenderbim/blenderbim/bim/module/document/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/document/__init__.py
@@ -20,35 +20,29 @@ import bpy
 from . import ui, prop, operator
 
 classes = (
-    operator.LoadInformation,
-    operator.LoadDocumentReferences,
-    operator.DisableDocumentEditingUI,
-    operator.EnableEditingDocument,
-    operator.DisableEditingDocument,
-    operator.AddInformation,
     operator.AddDocumentReference,
-    operator.EditInformation,
-    operator.EditDocumentReference,
-    operator.RemoveDocument,
-    operator.EnableAssigningDocument,
-    operator.DisableAssigningDocument,
+    operator.AddInformation,
     operator.AssignDocument,
+    operator.DisableDocumentEditingUI,
+    operator.DisableEditingDocument,
+    operator.EditDocument,
+    operator.EnableEditingDocument,
+    operator.LoadDocument,
+    operator.LoadParentDocument,
+    operator.LoadProjectDocuments,
+    operator.RemoveDocument,
     operator.UnassignDocument,
     prop.Document,
     prop.BIMDocumentProperties,
-    prop.BIMObjectDocumentProperties,
     ui.BIM_PT_documents,
     ui.BIM_PT_object_documents,
     ui.BIM_UL_documents,
-    ui.BIM_UL_object_documents,
 )
 
 
 def register():
     bpy.types.Scene.BIMDocumentProperties = bpy.props.PointerProperty(type=prop.BIMDocumentProperties)
-    bpy.types.Object.BIMObjectDocumentProperties = bpy.props.PointerProperty(type=prop.BIMObjectDocumentProperties)
 
 
 def unregister():
     del bpy.types.Scene.BIMDocumentProperties
-    del bpy.types.Object.BIMObjectDocumentProperties
diff --git a/src/blenderbim/blenderbim/bim/module/document/data.py b/src/blenderbim/blenderbim/bim/module/document/data.py
index 3718cb46a5..3b056bec32 100644
--- a/src/blenderbim/blenderbim/bim/module/document/data.py
+++ b/src/blenderbim/blenderbim/bim/module/document/data.py
@@ -16,6 +16,7 @@
 # You should have received a copy of the GNU General Public License
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
+import os
 import bpy
 import ifcopenshell
 import ifcopenshell.util.schema
@@ -35,17 +36,29 @@ class DocumentData:
     def load(cls):
         cls.data = {
             "total_information": cls.total_information(),
-            "total_references": cls.total_references(),
+            "parent_document": cls.parent_document(),
         }
         cls.is_loaded = True
 
     @classmethod
     def total_information(cls):
-        return len(tool.Ifc.get().by_type("IfcDocumentInformation"))
+        return len(
+            [
+                rel
+                for rel in tool.Ifc.get().by_type("IfcProject")[0].HasAssociations or []
+                if rel.is_a("IfcRelAssociatesDocument") and rel.RelatingDocument.is_a("IfcDocumentInformation")
+            ]
+        )
 
     @classmethod
-    def total_references(cls):
-        return len(tool.Ifc.get().by_type("IfcDocumentReference"))
+    def parent_document(cls):
+        props = bpy.context.scene.BIMDocumentProperties
+        if len(props.breadcrumbs):
+            parent = tool.Ifc.get().by_id(int(props.breadcrumbs[-1].name))
+            if tool.Ifc.get_schema() == "IFC2X3":
+                return str(parent.DocumentId)
+            return str(parent.Identification)
+        return ""
 
 
 class ObjectDocumentData:
@@ -69,16 +82,35 @@ class ObjectDocumentData:
             if rel.is_a("IfcRelAssociatesDocument"):
                 if not rel.RelatingDocument.is_a("IfcDocumentReference"):
                     continue
+
+                name = rel.RelatingDocument.Name
+                if not name and rel.RelatingDocument.ReferencedDocument:
+                    name = rel.RelatingDocument.ReferencedDocument.Name
+
                 if tool.Ifc.get_schema() == "IFC2X3":
                     identification = rel.RelatingDocument.ItemReference
+                    if not identification and rel.RelatingDocument.ReferencedDocument:
+                        identification = rel.RelatingDocument.ReferencedDocument.DocumentId
                 else:
                     identification = rel.RelatingDocument.Identification
+                    if not identification and rel.RelatingDocument.ReferencedDocument:
+                        identification = rel.RelatingDocument.ReferencedDocument.Identification
+
+                location = rel.RelatingDocument.Location
+                if location is None and rel.RelatingDocument.ReferencedDocument:
+                    location = rel.RelatingDocument.ReferencedDocument.Location
+                if location:
+                    if not "://" in location:
+                        if not os.path.isabs(location):
+                            location = os.path.abspath(os.path.join(os.path.dirname(tool.Ifc.get_path()), location))
+                        location = "file://" + location
+
                 results.append(
                     {
-                        "type": rel.RelatingDocument.is_a(),
                         "id": rel.RelatingDocument.id(),
                         "identification": identification,
-                        "name": rel.RelatingDocument.Name,
+                        "name": name,
+                        "location": location,
                     }
                 )
         return results
diff --git a/src/blenderbim/blenderbim/bim/module/document/operator.py b/src/blenderbim/blenderbim/bim/module/document/operator.py
index d97070a38d..32777cb314 100644
--- a/src/blenderbim/blenderbim/bim/module/document/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/document/operator.py
@@ -26,22 +26,32 @@ from blenderbim.bim.ifc import IfcStore
 from ifcopenshell.api.document.data import Data
 
 
-class LoadInformation(bpy.types.Operator, tool.Ifc.Operator):
-    bl_idname = "bim.load_information"
-    bl_label = "Load Information"
+class LoadProjectDocuments(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.load_project_documents"
+    bl_label = "Load Project Documents"
     bl_options = {"REGISTER", "UNDO"}
 
     def _execute(self, context):
-        core.load_information(tool.Document)
+        core.load_project_documents(tool.Document)
 
 
-class LoadDocumentReferences(bpy.types.Operator, tool.Ifc.Operator):
-    bl_idname = "bim.load_document_references"
-    bl_label = "Load Document References"
+class LoadDocument(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.load_document"
+    bl_label = "Load Document"
+    bl_options = {"REGISTER", "UNDO"}
+    document: bpy.props.IntProperty()
+
+    def _execute(self, context):
+        core.load_document(tool.Document, document=tool.Ifc.get().by_id(self.document))
+
+
+class LoadParentDocument(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.load_parent_document"
+    bl_label = "Load Parent Document"
     bl_options = {"REGISTER", "UNDO"}
 
     def _execute(self, context):
-        core.load_references(tool.Document)
+        core.load_parent_document(tool.Document)
 
 
 class DisableDocumentEditingUI(bpy.types.Operator, tool.Ifc.Operator):
@@ -90,24 +100,14 @@ class AddDocumentReference(bpy.types.Operator, tool.Ifc.Operator):
         core.add_reference(tool.Ifc, tool.Document)
 
 
-class EditInformation(bpy.types.Operator, tool.Ifc.Operator):
-    bl_idname = "bim.edit_information"
+class EditDocument(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.edit_document"
     bl_label = "Edit Information"
     bl_options = {"REGISTER", "UNDO"}
 
     def _execute(self, context):
         props = context.scene.BIMDocumentProperties
-        core.edit_information(tool.Ifc, tool.Document, information=tool.Ifc.get().by_id(props.active_document_id))
-
-
-class EditDocumentReference(bpy.types.Operator, tool.Ifc.Operator):
-    bl_idname = "bim.edit_document_reference"
-    bl_label = "Edit Document Reference"
-    bl_options = {"REGISTER", "UNDO"}
-
-    def _execute(self, context):
-        props = context.scene.BIMDocumentProperties
-        core.edit_reference(tool.Ifc, tool.Document, reference=tool.Ifc.get().by_id(props.active_document_id))
+        core.edit_document(tool.Ifc, tool.Document, document=tool.Ifc.get().by_id(props.active_document_id))
 
 
 class RemoveDocument(bpy.types.Operator, tool.Ifc.Operator):
@@ -120,28 +120,6 @@ class RemoveDocument(bpy.types.Operator, tool.Ifc.Operator):
         core.remove_document(tool.Ifc, tool.Document, document=tool.Ifc.get().by_id(self.document))
 
 
-class EnableAssigningDocument(bpy.types.Operator, tool.Ifc.Operator):
-    bl_idname = "bim.enable_assigning_document"
-    bl_label = "Enable Assigning Document"
-    bl_options = {"REGISTER", "UNDO"}
-    obj: bpy.props.StringProperty()
-
-    def _execute(self, context):
-        obj = bpy.data.objects.get(self.obj) if self.obj else context.active_object
-        core.enable_assigning_document(tool.Document, obj)
-
-
-class DisableAssigningDocument(bpy.types.Operator, tool.Ifc.Operator):
-    bl_idname = "bim.disable_assigning_document"
-    bl_label = "Disable Assigning Document"
-    bl_options = {"REGISTER", "UNDO"}
-    obj: bpy.props.StringProperty()
-
-    def _execute(self, context):
-        obj = bpy.data.objects.get(self.obj) if self.obj else context.active_object
-        core.enable_assigning_document(tool.Document, obj)
-
-
 class AssignDocument(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.assign_document"
     bl_label = "Assign Document"
diff --git a/src/blenderbim/blenderbim/bim/module/document/prop.py b/src/blenderbim/blenderbim/bim/module/document/prop.py
index a470e715ae..1a9c7412cf 100644
--- a/src/blenderbim/blenderbim/bim/module/document/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/document/prop.py
@@ -34,6 +34,7 @@ from bpy.props import (
 class Document(PropertyGroup):
     name: StringProperty(name="Name")
     identification: StringProperty(name="Identification")
+    is_information: BoolProperty(name="Is Information")
     ifc_definition_id: IntProperty(name="IFC Definition ID")
 
 
@@ -41,12 +42,6 @@ class BIMDocumentProperties(PropertyGroup):
     document_attributes: CollectionProperty(name="Document Attributes", type=Attribute)
     active_document_id: IntProperty(name="Active Document Id")
     documents: CollectionProperty(name="Documents", type=Document)
+    breadcrumbs: CollectionProperty(name="Breadcrumbs", type=StrProperty)
     active_document_index: IntProperty(name="Active Document Index")
-    is_editing: StringProperty(name="Is Editing")
-
-
-class BIMObjectDocumentProperties(PropertyGroup):
-    is_adding: StringProperty(name="Is Adding")
-    available_document_types: EnumProperty(
-        items=[(d, d, "") for d in ["IfcDocumentInformation", "IfcDocumentReference"]], name="Available Document Types"
-    )
+    is_editing: BoolProperty(name="Is Editing", default=False)
diff --git a/src/blenderbim/blenderbim/bim/module/document/ui.py b/src/blenderbim/blenderbim/bim/module/document/ui.py
index a13995f694..b5ee5efe93 100644
--- a/src/blenderbim/blenderbim/bim/module/document/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/document/ui.py
@@ -29,7 +29,7 @@ class BIM_PT_documents(Panel):
     bl_space_type = "PROPERTIES"
     bl_region_type = "WINDOW"
     bl_context = "scene"
-    bl_parent_id = "BIM_PT_collaboration"
+    bl_parent_id = "BIM_PT_project_setup"
 
     @classmethod
     def poll(cls, context):
@@ -41,34 +41,38 @@ class BIM_PT_documents(Panel):
 
         self.props = context.scene.BIMDocumentProperties
 
-        if not self.props.is_editing or self.props.is_editing == "information":
-            row = self.layout.row(align=True)
-            row.label(text="{} Documents Found".format(DocumentData.data["total_information"]), icon="FILE")
-            if self.props.is_editing == "information":
-                row.operator("bim.add_information", text="", icon="ADD")
-                row.operator("bim.disable_document_editing_ui", text="", icon="CANCEL")
-            else:
-                row.operator("bim.load_information", text="", icon="IMPORT")
-
-        if not self.props.is_editing or self.props.is_editing == "reference":
-            row = self.layout.row(align=True)
-            row.label(text="{} References Found".format(DocumentData.data["total_references"]), icon="FILE_HIDDEN")
-            if self.props.is_editing == "reference":
-                row.operator("bim.add_document_reference", text="", icon="ADD")
-                row.operator("bim.disable_document_editing_ui", text="", icon="CANCEL")
-            else:
-                row.operator("bim.load_document_references", text="", icon="IMPORT")
-
+        row = self.layout.row(align=True)
+        row.label(text="{} Documents Found".format(DocumentData.data["total_information"]), icon="FILE")
         if self.props.is_editing:
-            self.layout.template_list(
-                "BIM_UL_documents", "", self.props, "documents", self.props, "active_document_index"
-            )
+            row.operator("bim.disable_document_editing_ui", text="", icon="CANCEL")
+        else:
+            row.operator("bim.load_project_documents", text="", icon="IMPORT")
+
+        if not self.props.is_editing:
+            return
+
+        row = self.layout.row(align=True)
+        if self.props.breadcrumbs:
+            row.operator("bim.load_parent_document", text="", icon="FRAME_PREV")
+            row.label(text=DocumentData.data["parent_document"])
+        else:
+            row.alignment = "RIGHT"
+        row.operator("bim.add_information", text="", icon="ADD")
+        if self.props.breadcrumbs:
+            row.operator("bim.add_document_reference", text="", icon="FILE_HIDDEN")
 
         if self.props.active_document_id:
-            self.draw_editable_ui(context)
+            row.operator("bim.edit_document", text="", icon="CHECKMARK")
+            row.operator("bim.disable_editing_document", text="", icon="CANCEL")
+        elif self.props.documents and self.props.active_document_index < len(self.props.documents):
+            ifc_definition_id = self.props.documents[self.props.active_document_index].ifc_definition_id
+            row.operator("bim.enable_editing_document", text="", icon="GREASEPENCIL").document = ifc_definition_id
+            row.operator("bim.remove_document", text="", icon="X").document = ifc_definition_id
 
-    def draw_editable_ui(self, context):
-        draw_attributes(self.props.document_attributes, self.layout)
+        self.layout.template_list("BIM_UL_documents", "", self.props, "documents", self.props, "active_document_index")
+
+        if self.props.active_document_id:
+            draw_attributes(self.props.document_attributes, self.layout)
 
 
 class BIM_PT_object_documents(Panel):
@@ -94,8 +98,7 @@ class BIM_PT_object_documents(Panel):
 
         obj = context.active_object
         self.oprops = obj.BIMObjectProperties
-        self.sprops = context.scene.BIMDocumentProperties
-        self.props = obj.BIMObjectDocumentProperties
+        self.props = context.scene.BIMDocumentProperties
         self.file = IfcStore.get_file()
 
         self.draw_add_ui()
@@ -108,52 +111,46 @@ class BIM_PT_object_documents(Panel):
             row = self.layout.row(align=True)
             row.label(text=document["identification"] or "*", icon="FILE")
             row.label(text=document["name"] or "Unnamed")
+            if document["location"]:
+                row.operator("bim.open_uri", icon="URL", text="").uri = document["location"]
             row.operator("bim.unassign_document", text="", icon="X").document = document["id"]
 
     def draw_add_ui(self):
-        if self.props.is_adding:
+        if not self.props.is_editing:
             row = self.layout.row(align=True)
-            icon = "FILE" if self.props.is_adding == "IfcDocumentInformation" else "FILE_HIDDEN"
-            row.label(text="Adding {}".format(self.props.is_adding), icon=icon)
-            row.operator("bim.disable_assigning_document", text="", icon="CANCEL")
-            self.layout.template_list(
-                "BIM_UL_object_documents",
-                "",
-                self.sprops,
-                "documents",
-                self.sprops,
-                "active_document_index",
-            )
+            row.operator("bim.load_project_documents", text="Assign Document References", icon="ADD")
+            return
+
+        row = self.layout.row(align=True)
+        if self.props.breadcrumbs:
+            row.operator("bim.load_parent_document", text="", icon="FRAME_PREV")
+            row.label(text=DocumentData.data["parent_document"])
         else:
-            row = self.layout.row(align=True)
-            row.prop(self.props, "available_document_types", text="")
-            row.operator("bim.enable_assigning_document", text="", icon="ADD")
+            row.alignment = "RIGHT"
+
+        if self.props.documents and self.props.active_document_index < len(self.props.documents):
+            document = self.props.documents[self.props.active_document_index]
+            if not document.is_information:
+                row.operator("bim.assign_document", text="", icon="ADD").document = document.ifc_definition_id
+        row.operator("bim.disable_document_editing_ui", text="", icon="CANCEL")
+
+        self.layout.template_list("BIM_UL_documents", "", self.props, "documents", self.props, "active_document_index")
 
 
 class BIM_UL_documents(UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
         if item:
             row = layout.row(align=True)
-            row.label(text=item.identification)
-            row.label(text=item.name)
-            if context.scene.BIMDocumentProperties.active_document_id == item.ifc_definition_id:
-                if context.scene.BIMDocumentProperties.is_editing == "information":
-                    row.operator("bim.edit_information", text="", icon="CHECKMARK")
-                elif context.scene.BIMDocumentProperties.is_editing == "reference":
-                    row.operator("bim.edit_document_reference", text="", icon="CHECKMARK")
-                row.operator("bim.disable_editing_document", text="", icon="CANCEL")
-            elif context.scene.BIMDocumentProperties.active_document_id:
-                row.operator("bim.remove_document", text="", icon="X").document = item.ifc_definition_id
-            else:
-                op = row.operator("bim.enable_editing_document", text="", icon="GREASEPENCIL")
+
+            if item.is_information:
+                op = row.operator("bim.load_document", text="", emboss=False, icon="DISCLOSURE_TRI_RIGHT")
                 op.document = item.ifc_definition_id
-                row.operator("bim.remove_document", text="", icon="X").document = item.ifc_definition_id
+                row.label(text="", icon="FILE")
+            else:
+                row.label(text="", icon="BLANK1")
+                row.label(text="", icon="FILE_HIDDEN")
 
-
-class BIM_UL_object_documents(UIList):
-    def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
-        if item:
-            row = layout.row(align=True)
-            row.label(text=item.identification)
-            row.label(text=item.name)
-            row.operator("bim.assign_document", text="", icon="ADD").document = item.ifc_definition_id
+            split1 = row.split(factor=0.1)
+            split1.label(text=item.identification)
+            split2 = split1.split(factor=0.9)
+            split2.label(text=item.name)
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/__init__.py b/src/blenderbim/blenderbim/bim/module/drawing/__init__.py
index a2ac21cffc..795a33d173 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/__init__.py
@@ -33,6 +33,7 @@ classes = (
     operator.AddSheet,
     operator.BuildSchedule,
     operator.CleanWireframes,
+    operator.ContractSheet,
     operator.CopyGrid,
     operator.CreateDrawing,
     operator.CreateSheets,
@@ -45,12 +46,14 @@ classes = (
     operator.EditVectorStyle,
     operator.EnableEditingText,
     operator.EnableEditingTextProduct,
+    operator.ExpandSheet,
     operator.GenerateReferences,
     operator.LoadDrawings,
     operator.LoadSheets,
     operator.OpenSheet,
     operator.OpenView,
     operator.RemoveDrawing,
+    operator.RemoveDrawingFromSheet,
     operator.RemoveDrawingStyle,
     operator.RemoveDrawingStyleAttribute,
     operator.RemoveSchedule,
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/decoration.py b/src/blenderbim/blenderbim/bim/module/drawing/decoration.py
index 94ab57d4e3..f29e038f80 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/decoration.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/decoration.py
@@ -40,7 +40,7 @@ class BaseDecorator:
 
     DEF_GLSL = """
         #define PI 3.141592653589793
-        #define MAX_POINTS 32
+        #define MAX_POINTS 64
         #define CIRCLE_SEGS 12
     """
 
@@ -1125,15 +1125,15 @@ class GridDecorator(BaseDecorator):
         self.draw_label(context, text, p1, dir, vcenter=True, gap=0)
 
 
-class SectionViewDecorator(LevelDecorator):
-    objecttype = "SECTION"
+class ElevationDecorator(LevelDecorator):
+    objecttype = "ELEVATION"
 
     DEF_GLSL = (
         BaseDecorator.DEF_GLSL
         + """
         #define CIRCLE_SIZE 8.0
-        #define TRIANGLE_L 32.0
-        #define TRIANGLE_W 16.0
+        #define TRIANGLE_L 22.63
+        #define TRIANGLE_W 11.31
     """
     )
 
@@ -1144,12 +1144,14 @@ class SectionViewDecorator(LevelDecorator):
     layout(lines) in;
     layout(line_strip, max_vertices=MAX_POINTS) out;
 
-    void triangle_head(in vec4 dir, in vec4 side, in float length, in float width, out vec4 head[3]) {
-        vec4 nose = dir * length;
-        vec4 ear = side * width;
-        head[0] = vec4(0);
-        head[1] = nose * .5 + ear;
-        head[2] = nose;
+    void triangle_head(in vec4 side, in vec4 dir, in float length, in float width, in float radius, out vec4 head[5]) {
+        vec4 nose = side * length;
+        vec4 ear = dir * width;
+        head[0] = side * -radius;
+        head[1] = nose * -.5;
+        head[2] = vec4(0) + ear;
+        head[3] = nose * .5;
+        head[4] = side * radius;
     }
 
     void main() {
@@ -1160,75 +1162,206 @@ class SectionViewDecorator(LevelDecorator):
 
         vec4 p0w = CLIP2WIN(p0), p1w = CLIP2WIN(p1);
         vec4 edge = p1w - p0w, dir = normalize(edge);
-        vec4 gap = dir * viewportDrawingScale * TRIANGLE_L * .5;
         vec4 side = vec4(cross(vec3(dir.xy, 0), vec3(0, 0, 1)).xy, 0, 0);
         vec4 p;
 
         vec4 head[CIRCLE_SEGS];
         circle_head(viewportDrawingScale * CIRCLE_SIZE, head);
 
-        vec4 head3[3];
+        vec4 head5[5];
 
         // start edge circle
         for(int i=0; i<CIRCLE_SEGS; i++) {
-            p = p0w + gap + head[i];
+            p = p0w + head[i];
             gl_Position = WIN2CLIP(p);
             EmitVertex();
         }
-        p = p0w + gap + head[0];
+        p = p0w + head[0];
         gl_Position = WIN2CLIP(p);
         EmitVertex();
         EndPrimitive();
 
-        // start edge triangle
-        triangle_head(dir, -side, viewportDrawingScale * TRIANGLE_L, viewportDrawingScale * TRIANGLE_W, head3);
-        p = p0w + head3[0];
+        // edge triangle
+        triangle_head(side, dir, viewportDrawingScale * TRIANGLE_L, viewportDrawingScale * TRIANGLE_W, viewportDrawingScale * CIRCLE_SIZE, head5);
+        p = p0w + head5[0];
         gl_Position = WIN2CLIP(p);
         EmitVertex();
-        p = p0w + head3[1];
+        p = p0w + head5[1];
         gl_Position = WIN2CLIP(p);
         EmitVertex();
-        p = p0w + head3[2];
+        p = p0w + head5[2];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p0w + head5[3];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p0w + head5[4];
         gl_Position = WIN2CLIP(p);
         EmitVertex();
         EndPrimitive();
 
-        // end edge circle
-        for(int i=0; i<CIRCLE_SEGS; i++) {
-            p = p1w - gap + head[i];
-            gl_Position = WIN2CLIP(p);
-            EmitVertex();
-        }
-        p = p1w - gap + head[0];
+        // reference divider
+        p = p0w + normalize(vec4(-1, 0, 0, 0)) * viewportDrawingScale * CIRCLE_SIZE;
         gl_Position = WIN2CLIP(p);
         EmitVertex();
-        EndPrimitive();
-
-        // end edge triangle
-        triangle_head(-dir, -side, viewportDrawingScale * TRIANGLE_L, viewportDrawingScale * TRIANGLE_W, head3);
-        p = p1w + head3[0];
+        p = p0w + normalize(vec4(1, 0, 0, 0)) * viewportDrawingScale * CIRCLE_SIZE;
         gl_Position = WIN2CLIP(p);
         EmitVertex();
-        p = p1w + head3[1];
-        gl_Position = WIN2CLIP(p);
-        EmitVertex();
-        p = p1w + head3[2];
-        gl_Position = WIN2CLIP(p);
-        EmitVertex();
-        EndPrimitive();
-
-        // stem
-        gl_Position = p0;
-        EmitVertex();
-        gl_Position = p1;
-        EmitVertex();
         EndPrimitive();
     }
     """
 
     def decorate(self, context, obj):
-        verts, _, _ = self.get_path_geom(obj, topo=False)
-        self.draw_lines(context, obj, verts, [(0, 1)])
+        center = obj.matrix_world.translation
+        v1 = obj.matrix_world @ Vector((0, 0, 0))
+        v2 = obj.matrix_world @ Vector((0, 0, -1))
+        self.draw_lines(context, obj, [v1, v2], [(0, 1)])
+
+
+class SectionDecorator(LevelDecorator):
+    objecttype = "SECTION"
+
+    DEF_GLSL = (
+        BaseDecorator.DEF_GLSL
+        + """
+        #define CIRCLE_SIZE 8.0
+        #define TRIANGLE_L 22.63
+        #define TRIANGLE_W 11.31
+    """
+    )
+
+    GEOM_GLSL = """
+    uniform vec2 winsize;
+    uniform float viewportDrawingScale;
+
+    layout(lines) in;
+    layout(line_strip, max_vertices=MAX_POINTS) out;
+
+    void triangle_head(in vec4 side, in vec4 dir, in float length, in float width, in float radius, out vec4 head[5]) {
+        vec4 nose = side * length;
+        vec4 ear = dir * width;
+        head[0] = side * -radius;
+        head[1] = nose * -.5;
+        head[2] = vec4(0) + ear;
+        head[3] = nose * .5;
+        head[4] = side * radius;
+    }
+
+    void main() {
+        vec4 clip2win = matCLIP2WIN();
+        vec4 win2clip = matWIN2CLIP();
+
+        vec4 p0 = gl_in[0].gl_Position, p1 = gl_in[1].gl_Position;
+
+        vec4 p0w = CLIP2WIN(p0), p1w = CLIP2WIN(p1);
+        vec4 edge = p1w - p0w, side = normalize(edge);
+        vec4 gap = side * viewportDrawingScale * CIRCLE_SIZE;
+        vec4 dir = vec4(cross(vec3(side.xy, 0), vec3(0, 0, 1)).xy, 0, 0);
+        vec4 p;
+
+        vec4 head[CIRCLE_SEGS];
+        circle_head(viewportDrawingScale * CIRCLE_SIZE, head);
+
+        vec4 head5[5];
+
+        // start edge circle
+        for(int i=0; i<CIRCLE_SEGS; i++) {
+            p = p0w + head[i];
+            gl_Position = WIN2CLIP(p);
+            EmitVertex();
+        }
+        p = p0w + head[0];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        EndPrimitive();
+
+        // start edge triangle
+        triangle_head(side, dir, viewportDrawingScale * TRIANGLE_L, viewportDrawingScale * TRIANGLE_W, viewportDrawingScale * CIRCLE_SIZE, head5);
+        p = p0w + head5[0];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p0w + head5[1];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p0w + head5[2];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p0w + head5[3];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p0w + head5[4];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        EndPrimitive();
+
+        // start reference divider
+        p = p0w + normalize(vec4(-1, 0, 0, 0)) * viewportDrawingScale * CIRCLE_SIZE;
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p0w + normalize(vec4(1, 0, 0, 0)) * viewportDrawingScale * CIRCLE_SIZE;
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        EndPrimitive();
+
+        // end edge circle
+        for(int i=0; i<CIRCLE_SEGS; i++) {
+            p = p1w - head[i];
+            gl_Position = WIN2CLIP(p);
+            EmitVertex();
+        }
+        p = p1w - head[0];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        EndPrimitive();
+
+        // end edge triangle
+        triangle_head(side, dir, viewportDrawingScale * TRIANGLE_L, viewportDrawingScale * TRIANGLE_W, viewportDrawingScale * CIRCLE_SIZE, head5);
+        p = p1w + head5[0];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p1w + head5[1];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p1w + head5[2];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p1w + head5[3];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p1w + head5[4];
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        EndPrimitive();
+
+        // end reference divider
+        p = p1w + normalize(vec4(-1, 0, 0, 0)) * viewportDrawingScale * CIRCLE_SIZE;
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p1w + normalize(vec4(1, 0, 0, 0)) * viewportDrawingScale * CIRCLE_SIZE;
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        EndPrimitive();
+
+        // stem
+        p = p0w + gap;
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        p = p1w - gap;
+        gl_Position = WIN2CLIP(p);
+        EmitVertex();
+        EndPrimitive();
+    }
+    """
+
+    def decorate(self, context, obj):
+        if obj.data.is_editmode:
+            verts, idxs = self.get_editmesh_geom(obj)
+        else:
+            verts, idxs = self.get_mesh_geom(obj)
+        vert_map = {v.freeze(): (obj.matrix_world.inverted() @ v).x for v in verts}
+        verts = sorted(verts, key=lambda v: vert_map[v], reverse=True)
+        self.draw_lines(context, obj, verts, idxs)
+
 
 
 class TextDecorator(BaseDecorator):
@@ -1327,7 +1460,8 @@ class DecorationsHandler:
         SectionLevelDecorator,
         StairDecorator,
         BreakDecorator,
-        SectionViewDecorator,
+        SectionDecorator,
+        ElevationDecorator,
         TextDecorator,
     ]
 
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/helper.py b/src/blenderbim/blenderbim/bim/module/drawing/helper.py
index a776312739..c2dfd8c1eb 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/helper.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/helper.py
@@ -260,14 +260,11 @@ def format_distance(value, isArea=False, hide_units=True):
 def get_active_drawing(scene):
     """Get active drawing collection and camera"""
     props = scene.DocProperties
-    if props.active_drawing_index is None or len(props.drawings) == 0:
-        return None, None
     try:
-        drawing = props.active_drawing
-        camera = tool.Ifc.get_object(tool.Ifc.get().by_id(drawing.ifc_definition_id))
+        camera = tool.Ifc.get_object(tool.Ifc.get().by_id(props.active_drawing_id))
         return camera.users_collection[0], camera
-    except (KeyError, IndexError):
-        raise RuntimeError("missing drawing collection")
+    except:
+        return None, None
 
 
 def get_project_collection(scene):
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/operator.py b/src/blenderbim/blenderbim/bim/module/drawing/operator.py
index 75b026a49a..34b8cdfcd2 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/operator.py
@@ -82,6 +82,11 @@ class AddDrawing(bpy.types.Operator, Operator):
             target_view=self.props.target_view,
             location_hint=hint,
         )
+        try:
+            drawing = tool.Ifc.get().by_id(self.props.active_drawing_id)
+            core.sync_references(tool.Ifc, tool.Collector, tool.Drawing, drawing=drawing)
+        except:
+            pass
 
 
 class CreateDrawing(bpy.types.Operator):
@@ -301,12 +306,13 @@ class CreateDrawing(bpy.types.Operator):
             elements = set(ifc.by_type("IfcElement")) - set(ifc.by_type("IfcOpeningElement"))
 
             self.setup_serialiser(ifc)
-            cache_settings = ifcopenshell.geom.settings(DISABLE_TRIANGULATION=True)
             cache = IfcStore.get_cache()
             [cache.remove(guid) for guid in invalidated_guids]
 
             if target_view_contexts and elements:
-                geom_settings = ifcopenshell.geom.settings(DISABLE_TRIANGULATION=True, INCLUDE_CURVES=True)
+                geom_settings = ifcopenshell.geom.settings(
+                    DISABLE_TRIANGULATION=True, STRICT_TOLERANCE=True, INCLUDE_CURVES=True
+                )
                 geom_settings.set_context_ids(target_view_contexts)
                 it = ifcopenshell.geom.iterator(geom_settings, ifc, multiprocessing.cpu_count(), include=elements)
                 it.set_cache(cache)
@@ -317,18 +323,14 @@ class CreateDrawing(bpy.types.Operator):
                 elements -= processed
 
             if body_contexts and elements:
-                geom_settings = ifcopenshell.geom.settings(
-                    DISABLE_TRIANGULATION=True,
-                )
+                geom_settings = ifcopenshell.geom.settings(DISABLE_TRIANGULATION=True, STRICT_TOLERANCE=True)
                 geom_settings.set_context_ids(body_contexts)
                 it = ifcopenshell.geom.iterator(geom_settings, ifc, multiprocessing.cpu_count(), include=elements)
                 it.set_cache(cache)
                 for elem in self.yield_from_iterator(it):
                     self.serialiser.write(elem)
 
-            geom_settings = ifcopenshell.geom.settings(
-                DISABLE_TRIANGULATION=True,
-            )
+            geom_settings = ifcopenshell.geom.settings(DISABLE_TRIANGULATION=True, STRICT_TOLERANCE=True)
             it = ifcopenshell.geom.iterator(geom_settings, ifc, include=[self.camera_element])
             for elem in self.yield_from_iterator(it):
                 self.serialiser.write(elem)
@@ -345,7 +347,9 @@ class CreateDrawing(bpy.types.Operator):
         return svg_path
 
     def setup_serialiser(self, ifc):
-        self.svg_settings = ifcopenshell.geom.settings(DISABLE_TRIANGULATION=True, INCLUDE_CURVES=True)
+        self.svg_settings = ifcopenshell.geom.settings(
+            DISABLE_TRIANGULATION=True, STRICT_TOLERANCE=True, INCLUDE_CURVES=True
+        )
         self.svg_buffer = ifcopenshell.geom.serializers.buffer()
         self.serialiser = ifcopenshell.geom.serializers.svg(self.svg_buffer, self.svg_settings)
         self.serialiser.setFile(ifc)
@@ -453,6 +457,10 @@ class CreateDrawing(bpy.types.Operator):
                 svg_writer.annotations.setdefault("equal_objs", []).append(obj)
             elif element.ObjectType == "DIMENSION":
                 svg_writer.annotations.setdefault("dimension_objs", []).append(obj)
+            elif element.ObjectType == "ELEVATION":
+                svg_writer.annotations.setdefault("elevation_objs", []).append(obj)
+            elif element.ObjectType == "SECTION":
+                svg_writer.annotations.setdefault("section_objs", []).append(obj)
             elif element.ObjectType == "BREAKLINE":
                 svg_writer.annotations["break_obj"] = obj
             elif element.ObjectType == "HIDDEN_LINE":
@@ -563,7 +571,6 @@ class AddDrawingToSheet(bpy.types.Operator):
     bl_idname = "bim.add_drawing_to_sheet"
     bl_label = "Add Drawing To Sheet"
     bl_options = {"REGISTER", "UNDO"}
-    # TODO: check undo redo
 
     @classmethod
     def poll(cls, context):
@@ -572,9 +579,78 @@ class AddDrawingToSheet(bpy.types.Operator):
 
     def execute(self, context):
         props = context.scene.DocProperties
+        active_drawing = props.drawings[props.active_drawing_index]
+        active_sheet = props.sheets[props.active_sheet_index]
+        drawing = tool.Ifc.get().by_id(active_drawing.ifc_definition_id)
+        sheet = tool.Ifc.get().by_id(active_sheet.ifc_definition_id)
+        if not sheet.is_a("IfcDocumentInformation"):
+            return {"FINISHED"}
+
+        if tool.Ifc.get_schema() == "IFC2X3":
+            references = sheet.DocumentReferences or []
+        else:
+            references = sheet.HasDocumentReferences or []
+
+        has_drawing = False
+        for reference in references:
+            new = props.sheets.add()
+            new.ifc_definition_id = reference.id()
+            new.is_sheet = False
+
+            if tool.Ifc.get_schema() == "IFC2X3":
+                new.identification = reference.ItemReference or "X"
+                element = [r for r in tool.Ifc.by_type("IfcRelAssociatesDocument") if r.RelatingDocument == reference][
+                    0
+                ].RelatedObjects[0]
+            else:
+                new.identification = reference.Identification or "X"
+                element = reference.DocumentRefForObjects[0].RelatedObjects[0]
+            if element == drawing:
+                has_drawing = True
+                break
+
+        if has_drawing:
+            return {"FINISHED"}
+
+        reference = tool.Ifc.run("document.add_reference", information=sheet)
+        if tool.Ifc.get_schema() == "IFC2X3":
+            attributes = {"ItemReference": str(len(sheet.DocumentReferences or []))}
+        else:
+            attributes = {"Identification": str(len(sheet.HasDocumentReferences or []))}
+        tool.Ifc.run("document.edit_reference", reference=reference, attributes=attributes)
+        tool.Ifc.run("document.assign_document", product=drawing, document=reference)
         sheet_builder = sheeter.SheetBuilder()
         sheet_builder.data_dir = context.scene.BIMProperties.data_dir
-        sheet_builder.add_drawing(props.active_drawing.name, props.active_sheet.name)
+        sheet_builder.add_drawing(drawing, sheet)
+
+        tool.Drawing.import_sheets()
+        return {"FINISHED"}
+
+
+class RemoveDrawingFromSheet(bpy.types.Operator):
+    bl_idname = "bim.remove_drawing_from_sheet"
+    bl_label = "Remove Drawing From Sheet"
+    bl_options = {"REGISTER", "UNDO"}
+    reference: bpy.props.IntProperty()
+
+    def execute(self, context):
+        reference = tool.Ifc.get().by_id(self.reference)
+        if tool.Ifc.get_schema() == "IFC2X3":
+            sheet = reference.ReferenceToDocument[0]
+            drawing = [r for r in tool.Ifc.by_type("IfcRelAssociatesDocument") if r.RelatingDocument == reference][
+                0
+            ].RelatedObjects[0]
+        else:
+            sheet = reference.ReferencedDocument
+            drawing = reference.DocumentRefForObjects[0].RelatedObjects[0]
+
+        tool.Ifc.run("document.unassign_document", product=drawing, document=reference)
+        tool.Ifc.run("document.remove_reference", reference=reference)
+
+        sheet_builder = sheeter.SheetBuilder()
+        sheet_builder.data_dir = context.scene.BIMProperties.data_dir
+        sheet_builder.remove_drawing(drawing, sheet)
+        tool.Drawing.import_sheets()
         return {"FINISHED"}
 
 
@@ -590,7 +666,8 @@ class CreateSheets(bpy.types.Operator):
     def execute(self, context):
         scene = context.scene
         props = scene.DocProperties
-        name = props.active_sheet.name
+        active_sheet = props.sheets[props.active_sheet_index]
+        name = active_sheet.name
         sheet_builder = sheeter.SheetBuilder()
         sheet_builder.data_dir = scene.BIMProperties.data_dir
         sheet_builder.build(name)
@@ -677,7 +754,9 @@ class ActivateView(bpy.types.Operator):
 
                     project_collection.children["Views"].children[camera.users_collection[0].name].hide_viewport = False
         bpy.data.collections.get(camera.users_collection[0].name).hide_render = False
+        bpy.context.scene.DocProperties.active_drawing_id = self.drawing
         bpy.ops.bim.activate_drawing_style()
+        core.sync_references(tool.Ifc, tool.Collector, tool.Drawing, drawing=tool.Ifc.get().by_id(self.drawing))
         return {"FINISHED"}
 
 
@@ -777,12 +856,10 @@ class RemoveDrawing(bpy.types.Operator, Operator):
     bl_idname = "bim.remove_drawing"
     bl_label = "Remove Drawing"
     bl_options = {"REGISTER", "UNDO"}
-    index: bpy.props.IntProperty()
+    drawing: bpy.props.IntProperty()
 
     def _execute(self, context):
-        props = context.scene.DocProperties
-        drawing = tool.Ifc.get().by_id(props.drawings[self.index].ifc_definition_id)
-        core.remove_drawing(tool.Ifc, tool.Drawing, drawing=drawing)
+        core.remove_drawing(tool.Ifc, tool.Drawing, drawing=tool.Ifc.get().by_id(self.drawing))
 
 
 class AddDrawingStyle(bpy.types.Operator):
@@ -935,12 +1012,10 @@ class RemoveSheet(bpy.types.Operator, Operator):
     bl_idname = "bim.remove_sheet"
     bl_label = "Remove Sheet"
     bl_options = {"REGISTER", "UNDO"}
-    index: bpy.props.IntProperty()
+    sheet: bpy.props.IntProperty()
 
     def _execute(self, context):
-        self.props = context.scene.DocProperties
-        sheet = tool.Ifc.get().by_id(self.props.sheets[self.props.active_sheet_index].ifc_definition_id)
-        core.remove_sheet(tool.Ifc, tool.Drawing, sheet=sheet)
+        core.remove_sheet(tool.Ifc, tool.Drawing, sheet=tool.Ifc.get().by_id(self.sheet))
 
 
 class AddSchedule(bpy.types.Operator):
@@ -1070,8 +1145,10 @@ class CopyGrid(bpy.types.Operator):
         return helper.get_active_drawing(context.scene)[0] is not None
 
     def execute(self, context):
+        drawing = tool.Ifc.get_entity(context.scene.camera)
+        target_view = tool.Drawing.get_drawing_target_view(drawing)
         subcontext = ifcopenshell.util.representation.get_context(
-            IfcStore.get_file(), "Plan", "Annotation", context.scene.camera.data.BIMCameraProperties.target_view
+            IfcStore.get_file(), "Plan", "Annotation", target_view
         )
         if not subcontext:
             return {"FINISHED"}
@@ -1080,8 +1157,8 @@ class CopyGrid(bpy.types.Operator):
         view_coll, camera = helper.get_active_drawing(context.scene)
         is_ortho = camera.data.type == "ORTHO"
         bounds = helper.ortho_view_frame(camera.data) if is_ortho else None
-        clipping = is_ortho and camera.data.BIMCameraProperties.target_view in ("PLAN_VIEW", "REFLECTED_PLAN_VIEW")
-        elevating = is_ortho and camera.data.BIMCameraProperties.target_view in ("ELEVATION_VIEW", "SECTION_VIEW")
+        clipping = is_ortho and target_view in ("PLAN_VIEW", "REFLECTED_PLAN_VIEW")
+        elevating = is_ortho and target_view in ("ELEVATION_VIEW", "SECTION_VIEW")
 
         def grep(coll):
             results = []
@@ -1313,3 +1390,31 @@ class DisableEditingDrawings(bpy.types.Operator, Operator):
 
     def _execute(self, context):
         core.disable_editing_drawings(tool.Drawing)
+
+
+class ExpandSheet(bpy.types.Operator):
+    bl_idname = "bim.expand_sheet"
+    bl_label = "Expand Sheet"
+    bl_options = {"REGISTER", "UNDO"}
+    sheet: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.DocProperties
+        for sheet in [s for s in props.sheets if s.ifc_definition_id == self.sheet]:
+            sheet.is_expanded = True
+        core.load_sheets(tool.Drawing)
+        return {"FINISHED"}
+
+
+class ContractSheet(bpy.types.Operator):
+    bl_idname = "bim.contract_sheet"
+    bl_label = "Contract Sheet"
+    bl_options = {"REGISTER", "UNDO"}
+    sheet: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = context.scene.DocProperties
+        for sheet in [s for s in props.sheets if s.ifc_definition_id == self.sheet]:
+            sheet.is_expanded = False
+        core.load_sheets(tool.Drawing)
+        return {"FINISHED"}
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/prop.py b/src/blenderbim/blenderbim/bim/module/drawing/prop.py
index 31f36cfc3f..07e5b9b626 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/prop.py
@@ -199,6 +199,7 @@ class Variable(PropertyGroup):
 class Drawing(PropertyGroup):
     ifc_definition_id: IntProperty(name="IFC Definition ID")
     name: StringProperty(name="Name", update=update_drawing_name)
+    target_view: StringProperty(name="Target View")
 
 
 class Schedule(PropertyGroup):
@@ -220,8 +221,9 @@ class Sheet(PropertyGroup):
     ifc_definition_id: IntProperty(name="IFC Definition ID")
     identification: StringProperty(name="Identification")
     name: StringProperty(name="Name", get=get_name, set=set_name)
-    drawings: CollectionProperty(name="Drawings", type=Drawing)
-    active_drawing_index: IntProperty(name="Active Drawing Index")
+    is_sheet: BoolProperty(name="Is Sheet", default=False)
+    reference_type: StringProperty(name="Reference Type")
+    is_expanded: BoolProperty(name="Is Expanded", default=False)
 
 
 class DrawingStyle(PropertyGroup):
@@ -292,6 +294,7 @@ class DocProperties(PropertyGroup):
     )
     location_hint: EnumProperty(items=get_location_hint, name="Location Hint")
     drawings: CollectionProperty(name="Drawings", type=Drawing)
+    active_drawing_id: IntProperty(name="Active Drawing Id")
     active_drawing_index: IntProperty(name="Active Drawing Index")
     current_drawing_index: IntProperty(name="Current Drawing Index")
     schedules: CollectionProperty(name="Schedules", type=Schedule)
@@ -311,14 +314,6 @@ class DocProperties(PropertyGroup):
     def active_schedule(self):
         return self.schedules[self.active_schedule_index]
 
-    @property
-    def active_drawing(self):
-        return self.drawings[self.active_drawing_index]
-
-    @property
-    def active_sheet(self):
-        return self.sheets[self.active_sheet_index]
-
 
 class BIMCameraProperties(PropertyGroup):
     representation: StringProperty(name="Representation")
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/sheeter.py b/src/blenderbim/blenderbim/bim/module/drawing/sheeter.py
index db77c70e78..317a76e83a 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/sheeter.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/sheeter.py
@@ -16,11 +16,12 @@
 # You should have received a copy of the GNU General Public License
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
-import xml.etree.ElementTree as ET
-import urllib.parse
-import pystache
-import ntpath
 import os
+import ntpath
+import pystache
+import urllib.parse
+import xml.etree.ElementTree as ET
+import blenderbim.tool as tool
 from shutil import copy
 from xml.dom import minidom
 
@@ -59,11 +60,16 @@ class SheetBuilder:
         with open(sheet_path, "w") as f:
             f.write(minidom.parseString(ET.tostring(root)).toprettyxml(indent="    "))
 
-    def add_drawing(self, view_name, sheet_name):
-        sheet_path = os.path.join(self.data_dir, "sheets", sheet_name + ".svg")
-        view_path = os.path.join(self.data_dir, "diagrams", view_name + ".svg")
+    def add_drawing(self, drawing, sheet):
+        filename = drawing.Name
+        sheet_name = tool.Drawing.get_sheet_filename(sheet)
+        sheet_dir = os.path.join(self.data_dir, "sheets")
+        drawing_dir = os.path.join(self.data_dir, "diagrams")
+        sheet_path = os.path.join(sheet_dir, sheet_name + ".svg")
+        drawing_path = os.path.join(drawing_dir, filename + ".svg")
+        underlay_path = os.path.join(drawing_dir, filename + ".png")
 
-        if not os.path.isfile(view_path):
+        if not os.path.isfile(sheet_path):
             raise FileNotFoundError
 
         ET.register_namespace("", "http://www.w3.org/2000/svg")
@@ -72,7 +78,7 @@ class SheetBuilder:
         sheet_tree = ET.parse(sheet_path)
         sheet_root = sheet_tree.getroot()
 
-        view_tree = ET.parse(view_path)
+        view_tree = ET.parse(drawing_path)
         view_root = view_tree.getroot()
 
         # The view is placed into a group with a background image element.
@@ -80,26 +86,48 @@ class SheetBuilder:
         # here to accommodate browsers which do not nest images.
         view = ET.SubElement(sheet_root, "g")
         view.attrib["data-type"] = "drawing"
+        view.attrib["data-guid"] = drawing.GlobalId
         view_width = self.convert_to_mm(view_root.attrib.get("width"))
         view_height = self.convert_to_mm(view_root.attrib.get("height"))
 
-        background = ET.SubElement(view, "image")
-        background.attrib["xlink:href"] = "../diagrams/{}.png".format(view_name)
-        background.attrib["x"] = "30"
-        background.attrib["y"] = "30"
-        background.attrib["width"] = str(view_width)
-        background.attrib["height"] = str(view_height)
+        if os.path.isfile(underlay_path):
+            background = ET.SubElement(view, "image")
+            background.attrib["xlink:href"] = os.path.relpath(underlay_path, sheet_dir)
+            background.attrib["x"] = "30"
+            background.attrib["y"] = "30"
+            background.attrib["width"] = str(view_width)
+            background.attrib["height"] = str(view_height)
 
-        foreground = ET.SubElement(view, "image")
-        foreground.attrib["xlink:href"] = "../diagrams/{}.svg".format(view_name)
-        foreground.attrib["x"] = "30"
-        foreground.attrib["y"] = "30"
-        foreground.attrib["width"] = str(view_width)
-        foreground.attrib["height"] = str(view_height)
+        if os.path.isfile(drawing_path):
+            foreground = ET.SubElement(view, "image")
+            foreground.attrib["xlink:href"] = os.path.relpath(drawing_path, sheet_dir)
+            foreground.attrib["x"] = "30"
+            foreground.attrib["y"] = "30"
+            foreground.attrib["width"] = str(view_width)
+            foreground.attrib["height"] = str(view_height)
 
         self.add_view_title(30, view_height + 35, view)
         sheet_tree.write(sheet_path)
 
+    def remove_drawing(self, drawing, sheet):
+        sheet_name = tool.Drawing.get_sheet_filename(sheet)
+        sheet_dir = os.path.join(self.data_dir, "sheets")
+        sheet_path = os.path.join(sheet_dir, sheet_name + ".svg")
+
+        ET.register_namespace("", "http://www.w3.org/2000/svg")
+
+        sheet_tree = ET.parse(sheet_path)
+        sheet_root = sheet_tree.getroot()
+
+        print('removing drawing', sheet_root.findall("{http://www.w3.org/2000/svg}g"))
+        for g in sheet_root.findall("{http://www.w3.org/2000/svg}g"):
+            print('checking g', g)
+            if g.attrib["data-type"] == "drawing" and g.attrib["data-guid"] == drawing.GlobalId:
+                sheet_root.remove(g)
+                break
+
+        sheet_tree.write(sheet_path)
+
     def add_schedule(self, schedule_name, sheet_name):
         sheet_path = os.path.join(self.data_dir, "sheets", sheet_name + ".svg")
         view_path = os.path.join(self.data_dir, "schedules", schedule_name + ".svg")
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/svgwriter.py b/src/blenderbim/blenderbim/bim/module/drawing/svgwriter.py
index baabc5cef0..b13656735c 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/svgwriter.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/svgwriter.py
@@ -286,7 +286,15 @@ class SvgWriter:
                         },
                     )
                 )
-        self.draw_text_annotations()
+
+        for obj in self.annotations.get("elevation_objs", []):
+            self.draw_elevation_annotation(obj)
+
+        for obj in self.annotations.get("section_objs", []):
+            self.draw_section_annotation(obj)
+
+        for text_obj in self.annotations.get("text_objs", []):
+            self.draw_text_annotation(text_obj, text_obj.location)
 
     def draw_ifc_annotation(self):
         x_offset = self.raw_width / 2
@@ -425,9 +433,48 @@ class SvgWriter:
                 position = Vector((0, 0, 0))
             self.draw_text_annotation(obj, position)
 
-    def draw_text_annotations(self):
-        for text_obj in self.annotations.get("text_objs", []):
-            self.draw_text_annotation(text_obj, text_obj.location)
+    def draw_section_annotation(self, obj):
+        x_offset = self.raw_width / 2
+        y_offset = self.raw_height / 2
+
+        self.draw_line_annotation((obj, obj.data), ["solid"])
+
+        v1 = self.project_point_onto_camera(obj.matrix_world @ Vector((0, 0, 0)))
+        v2 = self.project_point_onto_camera(obj.matrix_world @ Vector((0, 0, -1)))
+        angle = -math.degrees((v2 - v1).xy.angle_signed(Vector((0, 1))))
+
+        for vert in obj.data.vertices:
+            point = obj.matrix_world @ vert.co
+            symbol_position = self.project_point_onto_camera(point)
+            symbol_position = Vector(((x_offset + symbol_position.x), (y_offset - symbol_position.y)))
+            transform = "rotate({}, {}, {})".format(
+                angle,
+                (symbol_position * self.scale)[0],
+                (symbol_position * self.scale)[1],
+            )
+
+            self.svg.add(self.svg.use("#section-arrow", insert=tuple(symbol_position * self.scale), transform=transform))
+            self.svg.add(self.svg.use("#section-tag", insert=tuple(symbol_position * self.scale)))
+
+    def draw_elevation_annotation(self, obj):
+        x_offset = self.raw_width / 2
+        y_offset = self.raw_height / 2
+        symbol_position = self.project_point_onto_camera(obj.location)
+        symbol_position = Vector(((x_offset + symbol_position.x), (y_offset - symbol_position.y)))
+
+        v1 = self.project_point_onto_camera(obj.matrix_world @ Vector((0, 0, 0)))
+        v2 = self.project_point_onto_camera(obj.matrix_world @ Vector((0, 0, -1)))
+        angle = -math.degrees((v2 - v1).xy.angle_signed(Vector((0, 1))))
+
+        transform = "rotate({}, {}, {})".format(
+            angle,
+            (symbol_position * self.scale)[0],
+            (symbol_position * self.scale)[1],
+        )
+
+        self.svg.add(self.svg.use("#elevation-arrow", insert=tuple(symbol_position * self.scale), transform=transform))
+        self.svg.add(self.svg.use("#elevation-tag", insert=tuple(symbol_position * self.scale)))
+
 
     def draw_text_annotation(self, text_obj, position):
         x_offset = self.raw_width / 2
@@ -646,6 +693,7 @@ class SvgWriter:
         )
 
     def project_point_onto_camera(self, point):
+        # TODO is this needlessly complex?
         return self.camera.matrix_world.inverted() @ geometry.intersect_line_plane(
             point.xyz,
             point.xyz - Vector(self.camera_projection),
diff --git a/src/blenderbim/blenderbim/bim/module/drawing/ui.py b/src/blenderbim/blenderbim/bim/module/drawing/ui.py
index 43ee18a7c1..55cc14b092 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/ui.py
@@ -172,14 +172,15 @@ class BIM_PT_drawings(Panel):
 
         if self.props.drawings:
             if self.props.active_drawing_index < len(self.props.drawings):
+                active_drawing = self.props.drawings[self.props.active_drawing_index]
                 row = self.layout.row(align=True)
                 row.alignment = "RIGHT"
                 op = row.operator("bim.open_view", icon="URL", text="")
-                op.view = self.props.active_drawing.name
+                op.view = active_drawing.name
                 op = row.operator("bim.activate_view", icon="OUTLINER_OB_CAMERA", text="")
-                op.drawing = self.props.active_drawing.ifc_definition_id
+                op.drawing = active_drawing.ifc_definition_id
                 row.operator("bim.create_drawing", text="", icon="OUTPUT")
-                row.operator("bim.remove_drawing", icon="X", text="").index = self.props.active_drawing_index
+                row.operator("bim.remove_drawing", icon="X", text="").drawing = active_drawing.ifc_definition_id
             self.layout.template_list(
                 "BIM_UL_drawinglist", "", self.props, "drawings", self.props, "active_drawing_index"
             )
@@ -245,14 +246,19 @@ class BIM_PT_sheets(Panel):
         row.operator("bim.add_sheet", text="", icon="ADD")
         row.operator("bim.disable_editing_sheets", text="", icon="CANCEL")
 
-        if self.props.sheets:
+        if self.props.sheets and self.props.active_sheet_index < len(self.props.sheets):
+            active_sheet = self.props.sheets[self.props.active_sheet_index]
             row = self.layout.row(align=True)
             row.alignment = "RIGHT"
             row.operator("bim.open_sheet", icon="URL", text="")
             row.operator("bim.add_drawing_to_sheet", icon="IMAGE_PLANE", text="")
             row.operator("bim.add_schedule_to_sheet", icon="PRESET_NEW", text="")
             row.operator("bim.create_sheets", icon="FILE_REFRESH", text="")
-            row.operator("bim.remove_sheet", icon="X", text="").index = self.props.active_sheet_index
+            if active_sheet.is_sheet:
+                row.operator("bim.remove_sheet", icon="X", text="").sheet = active_sheet.ifc_definition_id
+            else:
+                op = row.operator("bim.remove_drawing_from_sheet", icon="X", text="")
+                op.reference = active_sheet.ifc_definition_id
 
         self.layout.template_list("BIM_UL_sheets", "", self.props, "sheets", self.props, "active_sheet_index")
 
@@ -369,7 +375,16 @@ class BIM_UL_drawinglist(bpy.types.UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
         if item:
             row = layout.row(align=True)
-            row.prop(item, "name", text="", emboss=False)
+            icon = "UV_FACESEL"
+            if item.target_view == "ELEVATION_VIEW":
+                icon = "UV_VERTEXSEL"
+            elif item.target_view == "SECTION_VIEW":
+                icon = "UV_EDGESEL"
+            elif item.target_view == "REFLECTED_PLAN_VIEW":
+                icon = "XRAY"
+            elif item.target_view == "MODEL_VIEW":
+                icon = "SNAP_VOLUME"
+            row.prop(item, "name", text="", icon=icon, emboss=False)
         else:
             layout.label(text="", translate=False)
 
@@ -378,9 +393,22 @@ class BIM_UL_sheets(bpy.types.UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
         if item:
             row = layout.row(align=True)
-            split1 = row.split(factor=0.2)
-            split1.label(text=item.identification or "X")
-            split2 = split1.split(factor=0.8)
-            split2.label(text=item.name or "Unnamed")
+
+            if item.is_sheet:
+                if item.is_expanded:
+                    row.operator(
+                        "bim.contract_sheet", text="", emboss=False, icon="DISCLOSURE_TRI_DOWN"
+                    ).sheet = item.ifc_definition_id
+                else:
+                    row.operator(
+                        "bim.expand_sheet", text="", emboss=False, icon="DISCLOSURE_TRI_RIGHT"
+                    ).sheet = item.ifc_definition_id
+            else:
+                row.label(text="", icon="BLANK1")
+                if item.reference_type == "DRAWING":
+                    row.label(text="", icon="IMAGE_DATA")
+
+            name = "{} - {}".format(item.identification or "X", item.name or "Unnamed")
+            row.label(text=name)
         else:
             layout.label(text="", translate=False)
diff --git a/src/blenderbim/blenderbim/bim/module/geometry/operator.py b/src/blenderbim/blenderbim/bim/module/geometry/operator.py
index 5660ee76b3..8f8c301913 100644
--- a/src/blenderbim/blenderbim/bim/module/geometry/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/geometry/operator.py
@@ -157,6 +157,9 @@ class UpdateRepresentation(bpy.types.Operator):
     def update_obj_mesh_representation(self, context, obj):
         product = self.file.by_id(obj.BIMObjectProperties.ifc_definition_id)
 
+        if not product.is_a("IfcGridAxis"):
+            tool.Geometry.clear_cache(product)
+
         if product.is_a("IfcGridAxis"):
             ifcopenshell.api.run("grid.create_axis_curve", self.file, **{"axis_curve": obj, "grid_axis": product})
             return
@@ -355,6 +358,7 @@ class OverrideDeleteTrait:
 class OverrideDelete(bpy.types.Operator, OverrideDeleteTrait):
     bl_idname = "object.delete"
     bl_label = "Delete"
+    bl_options = {"REGISTER", "UNDO"}
     use_global: bpy.props.BoolProperty(default=False)
     confirm: bpy.props.BoolProperty(default=True)
 
@@ -368,21 +372,29 @@ class OverrideDelete(bpy.types.Operator, OverrideDeleteTrait):
             return IfcStore.execute_ifc_operator(self, context)
         for obj in context.selected_objects:
             bpy.data.objects.remove(obj)
+        # Required otherwise gizmos are still visible
+        context.view_layer.objects.active = None
         return {"FINISHED"}
 
     def invoke(self, context, event):
-        return context.window_manager.invoke_confirm(self, event)
+        if self.confirm:
+            return context.window_manager.invoke_confirm(self, event)
+        self.confirm = True
+        return self.execute(context)
 
     def _execute(self, context):
         for obj in context.selected_objects:
             self.delete_ifc_object(obj)
             bpy.data.objects.remove(obj)
+        # Required otherwise gizmos are still visible
+        context.view_layer.objects.active = None
         return {"FINISHED"}
 
 
 class OverrideOutlinerDelete(bpy.types.Operator, OverrideDeleteTrait):
     bl_idname = "outliner.delete"
     bl_label = "Delete"
+    bl_options = {"REGISTER", "UNDO"}
     hierarchy: bpy.props.BoolProperty(default=False)
 
     @classmethod
@@ -405,7 +417,6 @@ class OverrideOutlinerDelete(bpy.types.Operator, OverrideDeleteTrait):
             if item.bl_rna.identifier == "Collection":
                 collection = bpy.data.collections.get(item.name)
                 collection_data = self.get_collection_objects_and_children(collection)
-                print(collection_data)
                 objects_to_delete |= collection_data["objects"]
                 collections_to_delete |= collection_data["children"]
                 collections_to_delete.add(collection)
@@ -453,6 +464,7 @@ class OverrideOutlinerDelete(bpy.types.Operator, OverrideDeleteTrait):
 class OverrideDuplicateMove(bpy.types.Operator):
     bl_idname = "object.duplicate_move"
     bl_label = "Duplicate Objects"
+    bl_options = {"REGISTER", "UNDO"}
 
     @classmethod
     def poll(cls, context):
diff --git a/src/blenderbim/blenderbim/bim/module/material/__init__.py b/src/blenderbim/blenderbim/bim/module/material/__init__.py
index dc45495d16..8ba682ae5c 100644
--- a/src/blenderbim/blenderbim/bim/module/material/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/material/__init__.py
@@ -21,37 +21,47 @@ from . import ui, prop, operator
 
 classes = (
     operator.AddConstituent,
-    operator.AddDefaultMaterial,
     operator.AddLayer,
     operator.AddListItem,
     operator.AddMaterial,
+    operator.AddMaterialSet,
     operator.AddProfile,
     operator.AssignMaterial,
     operator.AssignParameterizedProfile,
     operator.CopyMaterial,
     operator.DisableEditingAssignedMaterial,
     operator.DisableEditingMaterialSetItem,
+    operator.DisableEditingMaterials,
     operator.EditAssignedMaterial,
     operator.EditMaterialSetItem,
     operator.EnableEditingAssignedMaterial,
     operator.EnableEditingMaterialSetItem,
+    operator.LoadMaterials,
     operator.RemoveConstituent,
     operator.RemoveLayer,
     operator.RemoveListItem,
     operator.RemoveMaterial,
+    operator.RemoveMaterialSet,
     operator.RemoveProfile,
     operator.ReorderMaterialSetItem,
+    operator.SelectByMaterial,
     operator.UnassignMaterial,
     operator.UnlinkMaterial,
+    prop.Material,
+    prop.BIMMaterialProperties,
     prop.BIMObjectMaterialProperties,
+    ui.BIM_PT_materials,
     ui.BIM_PT_material,
     ui.BIM_PT_object_material,
+    ui.BIM_UL_materials,
 )
 
 
 def register():
+    bpy.types.Scene.BIMMaterialProperties = bpy.props.PointerProperty(type=prop.BIMMaterialProperties)
     bpy.types.Object.BIMObjectMaterialProperties = bpy.props.PointerProperty(type=prop.BIMObjectMaterialProperties)
 
 
 def unregister():
+    del bpy.types.Scene.BIMMaterialProperties
     del bpy.types.Object.BIMObjectMaterialProperties
diff --git a/src/blenderbim/blenderbim/bim/module/material/data.py b/src/blenderbim/blenderbim/bim/module/material/data.py
new file mode 100644
index 0000000000..a327e31ab8
--- /dev/null
+++ b/src/blenderbim/blenderbim/bim/module/material/data.py
@@ -0,0 +1,86 @@
+# BlenderBIM Add-on - OpenBIM Blender Add-on
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of BlenderBIM Add-on.
+#
+# BlenderBIM Add-on is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# BlenderBIM Add-on is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import bpy
+import ifcopenshell
+import ifcopenshell.util.schema
+import blenderbim.tool as tool
+
+
+def refresh():
+    MaterialsData.is_loaded = False
+    ObjectMaterialData.is_loaded = False
+
+
+class MaterialsData:
+    data = {}
+    is_loaded = False
+
+    @classmethod
+    def load(cls):
+        cls.data = {
+            "total_materials": cls.total_materials(),
+            "material_types": cls.material_types(),
+        }
+        cls.is_loaded = True
+
+    @classmethod
+    def total_materials(cls):
+        if tool.Ifc.get_schema() == "IFC2X3":
+            return (
+                len(tool.Ifc.get().by_type("IfcMaterial"))
+                + len(tool.Ifc.get().by_type("IfcMaterialLayerSet"))
+                + len(tool.Ifc.get().by_type("IfcMaterialList"))
+            )
+        return (
+            len(tool.Ifc.get().by_type("IfcMaterial"))
+            + len(tool.Ifc.get().by_type("IfcMaterialConstituentSet"))
+            + len(tool.Ifc.get().by_type("IfcMaterialLayerSet"))
+            + len(tool.Ifc.get().by_type("IfcMaterialProfileSet"))
+            + len(tool.Ifc.get().by_type("IfcMaterialList"))
+        )
+
+    @classmethod
+    def material_types(cls):
+        material_types = [
+            "IfcMaterial",
+            "IfcMaterialConstituentSet",
+            "IfcMaterialLayerSet",
+            "IfcMaterialProfileSet",
+            "IfcMaterialList",
+        ]
+        if tool.Ifc.get_schema() == "IFC2X3":
+            material_types = ["IfcMaterial", "IfcMaterialLayerSet", "IfcMaterialList"]
+        return [(m, m, "") for m in material_types]
+
+
+class ObjectMaterialData:
+    data = {}
+    is_loaded = False
+
+    @classmethod
+    def load(cls):
+        cls.data = {
+            "materials": cls.materials(),
+        }
+        cls.is_loaded = True
+
+    @classmethod
+    def materials(cls):
+        return sorted([(str(m.id()), m.Name or "Unnamed", "") for m in tool.Ifc.get().by_type("IfcMaterial")], key=lambda x: x[1])
diff --git a/src/blenderbim/blenderbim/bim/module/material/operator.py b/src/blenderbim/blenderbim/bim/module/material/operator.py
index 8fc169ff0e..37e4781581 100644
--- a/src/blenderbim/blenderbim/bim/module/material/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/material/operator.py
@@ -31,11 +31,32 @@ from ifcopenshell.api.material.data import Data
 from ifcopenshell.api.profile.data import Data as ProfileData
 
 
-class Operator:
-    def execute(self, context):
-        IfcStore.execute_ifc_operator(self, context)
-        blenderbim.bim.handler.refresh_ui_data()
-        return {"FINISHED"}
+class LoadMaterials(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.load_materials"
+    bl_label = "Load Materials"
+    bl_options = {"REGISTER", "UNDO"}
+
+    def _execute(self, context):
+        core.load_materials(tool.Material, context.scene.BIMMaterialProperties.material_type)
+
+
+class DisableEditingMaterials(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.disable_editing_materials"
+    bl_label = "Disable Editing Materials"
+    bl_options = {"REGISTER", "UNDO"}
+
+    def _execute(self, context):
+        core.disable_editing_materials(tool.Material)
+
+
+class SelectByMaterial(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.select_by_material"
+    bl_label = "Select By Material"
+    bl_options = {"REGISTER", "UNDO"}
+    material: bpy.props.IntProperty()
+
+    def _execute(self, context):
+        core.select_by_material(tool.Material, material=tool.Ifc.get().by_id(self.material))
 
 
 class AssignParameterizedProfile(bpy.types.Operator):
@@ -68,70 +89,54 @@ class AssignParameterizedProfile(bpy.types.Operator):
         return {"FINISHED"}
 
 
-class AddDefaultMaterial(bpy.types.Operator, Operator):
-    bl_idname = "bim.add_default_material"
-    bl_label = "Add Default Material"
-    bl_options = {"REGISTER", "UNDO"}
-
-    def _execute(self, context):
-        core.add_default_material(tool.Ifc, tool.Material)
-        Data.load(IfcStore.get_file())
-
-
-class AddMaterial(bpy.types.Operator):
+class AddMaterial(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.add_material"
     bl_label = "Add Material"
     bl_options = {"REGISTER", "UNDO"}
     obj: bpy.props.StringProperty()
 
-    def execute(self, context):
-        return IfcStore.execute_ifc_operator(self, context)
-
     def _execute(self, context):
-        obj = bpy.data.materials.get(self.obj) if self.obj else context.active_object.active_material
-        self.file = IfcStore.get_file()
-        result = ifcopenshell.api.run("material.add_material", self.file, **{"name": obj.name})
-        IfcStore.link_element(result, obj)
-        if obj.BIMMaterialProperties.ifc_style_id:
-            context = ifcopenshell.util.representation.get_context(self.file, "Model", "Body", "MODEL_VIEW")
-            if context:
-                ifcopenshell.api.run(
-                    "style.assign_material_style",
-                    self.file,
-                    **{
-                        "material": result,
-                        "style": self.file.by_id(obj.BIMMaterialProperties.ifc_style_id),
-                        "context": context,
-                    },
-                )
+        obj = bpy.data.materials.get(self.obj) if self.obj else None
+        core.add_material(tool.Ifc, tool.Material, tool.Style, obj=obj)
         Data.load(IfcStore.get_file())
         material_prop_purge()
-        return {"FINISHED"}
 
 
-class RemoveMaterial(bpy.types.Operator):
+class AddMaterialSet(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.add_material_set"
+    bl_label = "Add Material Set"
+    bl_options = {"REGISTER", "UNDO"}
+    set_type: bpy.props.StringProperty()
+
+    def _execute(self, context):
+        core.add_material_set(tool.Ifc, tool.Material, set_type=self.set_type)
+        Data.load(IfcStore.get_file())
+        material_prop_purge()
+
+
+class RemoveMaterial(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.remove_material"
     bl_label = "Remove Material"
     bl_options = {"REGISTER", "UNDO"}
-    obj: bpy.props.StringProperty()
-
-    def execute(self, context):
-        return IfcStore.execute_ifc_operator(self, context)
+    material: bpy.props.IntProperty()
 
     def _execute(self, context):
-        obj = bpy.data.materials.get(self.obj) if self.obj else context.active_object.active_material
-        self.file = IfcStore.get_file()
-        result = ifcopenshell.api.run(
-            "material.remove_material",
-            self.file,
-            **{"material": self.file.by_id(obj.BIMObjectProperties.ifc_definition_id)},
-        )
-        obj.BIMObjectProperties.ifc_definition_id = 0
+        core.remove_material(tool.Ifc, tool.Material, tool.Style, material=tool.Ifc.get().by_id(self.material))
         Data.load(IfcStore.get_file())
-        return {"FINISHED"}
 
 
-class UnlinkMaterial(bpy.types.Operator, Operator):
+class RemoveMaterialSet(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.remove_material_set"
+    bl_label = "Remove Material Set"
+    bl_options = {"REGISTER", "UNDO"}
+    material: bpy.props.IntProperty()
+
+    def _execute(self, context):
+        core.remove_material_set(tool.Ifc, tool.Material, material=tool.Ifc.get().by_id(self.material))
+        Data.load(IfcStore.get_file())
+
+
+class UnlinkMaterial(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.unlink_material"
     bl_label = "Unlink Material"
     bl_options = {"REGISTER", "UNDO"}
diff --git a/src/blenderbim/blenderbim/bim/module/material/prop.py b/src/blenderbim/blenderbim/bim/module/material/prop.py
index 660303d471..349d132452 100644
--- a/src/blenderbim/blenderbim/bim/module/material/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/material/prop.py
@@ -18,6 +18,7 @@
 
 import bpy
 from ifcopenshell.api.material.data import Data
+from blenderbim.bim.module.material.data import MaterialsData, ObjectMaterialData
 from blenderbim.bim.ifc import IfcStore
 from blenderbim.bim.prop import StrProperty, Attribute
 from bpy.types import PropertyGroup
@@ -32,18 +33,15 @@ from bpy.props import (
     CollectionProperty,
 )
 
-materials_enum = []
 materialtypes_enum = []
 profileclasses_enum = []
 parameterizedprofileclasses_enum = []
 
 
 def purge():
-    global materials_enum
     global materialtypes_enum
     global profileclasses_enum
     global parameterizedprofileclasses_enum
-    materials_enum = []
     materialtypes_enum = []
     profileclasses_enum = []
     parameterizedprofileclasses_enum = []
@@ -77,12 +75,10 @@ def getParameterizedProfileClasses(self, context):
     return parameterizedprofileclasses_enum
 
 
-def getMaterials(self, context):
-    global materials_enum
-    if len(materials_enum) == 0 and IfcStore.get_file():
-        materials_enum.clear()
-        materials_enum = [(str(m_id), m["Name"], "") for m_id, m in Data.materials.items()]
-    return materials_enum
+def get_materials(self, context):
+    if not ObjectMaterialData.is_loaded:
+        ObjectMaterialData.load()
+    return ObjectMaterialData.data["materials"]
 
 
 def getMaterialTypes(self, context):
@@ -104,9 +100,28 @@ def getMaterialTypes(self, context):
     return materialtypes_enum
 
 
+def get_material_types(self, context):
+    if not MaterialsData.is_loaded:
+        MaterialsData.load()
+    return MaterialsData.data["material_types"]
+
+
+class Material(PropertyGroup):
+    name: StringProperty(name="Name")
+    ifc_definition_id: IntProperty(name="IFC Definition ID")
+    total_elements: IntProperty(name="Total Elements")
+
+
+class BIMMaterialProperties(PropertyGroup):
+    is_editing: BoolProperty(name="Is Editing", default=False)
+    material_type: EnumProperty(items=get_material_types, name="Material Type")
+    materials: CollectionProperty(name="Materials", type=Material)
+    active_material_index: IntProperty(name="Active Material Index")
+
+
 class BIMObjectMaterialProperties(PropertyGroup):
     material_type: EnumProperty(items=getMaterialTypes, name="Material Type")
-    material: EnumProperty(items=getMaterials, name="Material")
+    material: EnumProperty(items=get_materials, name="Material")
     is_editing: BoolProperty(name="Is Editing", default=False)
     material_set_usage_attributes: CollectionProperty(name="Material Set Usage Attributes", type=Attribute)
     material_set_attributes: CollectionProperty(name="Material Set Attributes", type=Attribute)
@@ -115,7 +130,7 @@ class BIMObjectMaterialProperties(PropertyGroup):
     material_set_item_profile_attributes: CollectionProperty(
         name="Material Set Item Profile Attributes", type=Attribute
     )
-    material_set_item_material: EnumProperty(items=getMaterials, name="Material")
+    material_set_item_material: EnumProperty(items=get_materials, name="Material")
     profile_classes: EnumProperty(items=getProfileClasses, name="Profile Classes")
     parameterized_profile_classes: EnumProperty(
         items=getParameterizedProfileClasses, name="Parameterized Profile Classes"
diff --git a/src/blenderbim/blenderbim/bim/module/material/ui.py b/src/blenderbim/blenderbim/bim/module/material/ui.py
index f7f51e2f03..818d59cedb 100644
--- a/src/blenderbim/blenderbim/bim/module/material/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/material/ui.py
@@ -17,11 +17,62 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import blenderbim.bim.helper
-from bpy.types import Panel
+from bpy.types import Panel, UIList
 from ifcopenshell.api.material.data import Data
 from ifcopenshell.api.profile.data import Data as ProfileData
 from blenderbim.bim.ifc import IfcStore
 from blenderbim.bim.helper import draw_attributes
+from blenderbim.bim.module.material.data import MaterialsData, ObjectMaterialData
+
+
+class BIM_PT_materials(Panel):
+    bl_label = "IFC Materials"
+    bl_idname = "BIM_PT_materials"
+    bl_options = {"DEFAULT_CLOSED"}
+    bl_space_type = "PROPERTIES"
+    bl_region_type = "WINDOW"
+    bl_context = "scene"
+    bl_parent_id = "BIM_PT_geometry"
+
+    @classmethod
+    def poll(cls, context):
+        return IfcStore.get_file()
+
+    def draw(self, context):
+        if not MaterialsData.is_loaded:
+            MaterialsData.load()
+
+        self.props = context.scene.BIMMaterialProperties
+
+        row = self.layout.row(align=True)
+        row.label(text="{} Materials Found".format(MaterialsData.data["total_materials"]), icon="MATERIAL")
+        if self.props.is_editing:
+            row.operator("bim.disable_editing_materials", text="", icon="CANCEL")
+        else:
+            row = self.layout.row(align=True)
+            row.prop(self.props, "material_type", text="")
+            row.operator("bim.load_materials", text="", icon="IMPORT")
+            return
+
+        row = self.layout.row(align=True)
+        row.alignment = "RIGHT"
+
+        if self.props.material_type == "IfcMaterial":
+            row.operator("bim.add_material", text="", icon="ADD")
+            if self.props.materials and self.props.active_material_index < len(self.props.materials):
+                material = self.props.materials[self.props.active_material_index]
+                op = row.operator("bim.select_by_material", text="", icon="RESTRICT_SELECT_OFF")
+                op.material = material.ifc_definition_id
+                row.operator("bim.remove_material", text="", icon="X").material = material.ifc_definition_id
+        else:
+            row.operator("bim.add_material_set", text="", icon="ADD").set_type = self.props.material_type
+            if self.props.materials and self.props.active_material_index < len(self.props.materials):
+                material = self.props.materials[self.props.active_material_index]
+                op = row.operator("bim.select_by_material", text="", icon="RESTRICT_SELECT_OFF")
+                op.material = material.ifc_definition_id
+                row.operator("bim.remove_material_set", text="", icon="X").material = material.ifc_definition_id
+
+        self.layout.template_list("BIM_UL_materials", "", self.props, "materials", self.props, "active_material_index")
 
 
 class BIM_PT_material(Panel):
@@ -37,11 +88,13 @@ class BIM_PT_material(Panel):
 
     def draw(self, context):
         row = self.layout.row(align=True)
-        if bool(context.active_object.active_material.BIMObjectProperties.ifc_definition_id):
-            row.operator("bim.remove_material", icon="X", text="Remove IFC Material")
+        material_id = context.active_object.active_material.BIMObjectProperties.ifc_definition_id
+        if bool(material_id):
+            row.operator("bim.remove_material", icon="X", text="Remove IFC Material").material = material_id
             row.operator("bim.unlink_material", icon="UNLINKED", text="")
         else:
-            row.operator("bim.add_material", icon="ADD", text="Create IFC Material")
+            op = row.operator("bim.add_material", icon="ADD", text="Create IFC Material")
+            op.obj = context.active_object.active_material.name
 
 
 class BIM_PT_object_material(Panel):
@@ -66,6 +119,9 @@ class BIM_PT_object_material(Panel):
         return True
 
     def draw(self, context):
+        if not ObjectMaterialData.is_loaded:
+            ObjectMaterialData.load()
+
         self.file = IfcStore.get_file()
         self.oprops = context.active_object.BIMObjectProperties
         self.props = context.active_object.BIMObjectMaterialProperties
@@ -77,10 +133,10 @@ class BIM_PT_object_material(Panel):
             ProfileData.load(self.file)
         self.product_data = Data.products[self.oprops.ifc_definition_id]
 
-        if not Data.materials:
+        if not ObjectMaterialData.data["materials"]:
             row = self.layout.row(align=True)
             row.label(text="No Materials Available")
-            row.operator("bim.add_default_material", icon="ADD", text="")
+            row.operator("bim.add_material", icon="ADD", text="").obj = ""
             return
 
         if self.product_data:
@@ -333,3 +389,13 @@ class BIM_PT_object_material(Panel):
         if total_thickness:
             row = self.layout.row(align=True)
             row.label(text=f"Total Thickness: {total_thickness:.3f}")
+
+
+class BIM_UL_materials(UIList):
+    def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
+        if item:
+            row = layout.row(align=True)
+            row.label(text=item.name)
+            row2 = row.row()
+            row2.alignment = "RIGHT"
+            row2.label(text=str(item.total_elements))
diff --git a/src/blenderbim/blenderbim/bim/module/model/data.py b/src/blenderbim/blenderbim/bim/module/model/data.py
index 704b4f5228..1ee9a3f7be 100644
--- a/src/blenderbim/blenderbim/bim/module/model/data.py
+++ b/src/blenderbim/blenderbim/bim/module/model/data.py
@@ -39,7 +39,12 @@ class AuthoringData:
     @classmethod
     def ifc_classes(cls):
         results = []
-        classes = {e.is_a() for e in tool.Ifc.get().by_type("IfcElementType")}
+        classes = {
+            e.is_a()
+            for e in tool.Ifc.get().by_type("IfcElementType")
+            + tool.Ifc.get().by_type("IfcDoorStyle")
+            + tool.Ifc.get().by_type("IfcWindowStyle")
+        }
         results.extend([(c, c, "") for c in sorted(classes)])
         return results
 
diff --git a/src/blenderbim/blenderbim/bim/module/model/handler.py b/src/blenderbim/blenderbim/bim/module/model/handler.py
index 894a3873cb..407d896e16 100644
--- a/src/blenderbim/blenderbim/bim/module/model/handler.py
+++ b/src/blenderbim/blenderbim/bim/module/model/handler.py
@@ -27,6 +27,7 @@ from bpy.app.handlers import persistent
 @persistent
 def load_post(*args):
     ifcopenshell.api.add_pre_listener("attribute.edit_attributes", "BlenderBIM.Root.SyncName", root.sync_name)
+    ifcopenshell.api.add_pre_listener("style.edit_presentation_style", "BlenderBIM.Root.SyncStyleName", root.sync_name)
 
     ifcopenshell.api.add_post_listener(
         "geometry.add_representation", "BlenderBIM.Product.GenerateBox", product.generate_box
diff --git a/src/blenderbim/blenderbim/bim/module/model/mep.py b/src/blenderbim/blenderbim/bim/module/model/mep.py
index 14784936d4..e971318d78 100644
--- a/src/blenderbim/blenderbim/bim/module/model/mep.py
+++ b/src/blenderbim/blenderbim/bim/module/model/mep.py
@@ -34,7 +34,6 @@ from math import pi, degrees
 from mathutils import Vector, Matrix
 
 
-
 class MepGenerator:
     def __init__(self, relating_type):
         self.relating_type = relating_type
diff --git a/src/blenderbim/blenderbim/bim/module/model/root.py b/src/blenderbim/blenderbim/bim/module/model/root.py
index 65c72152f1..a3a72e6e98 100644
--- a/src/blenderbim/blenderbim/bim/module/model/root.py
+++ b/src/blenderbim/blenderbim/bim/module/model/root.py
@@ -17,24 +17,34 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import bpy
+import blenderbim.bim.handler
+import blenderbim.tool as tool
 from blenderbim.bim.ifc import IfcStore
-from ifcopenshell.api.style.data import Data as StyleData
 
 
 def sync_name(usecase_path, ifc_file, settings):
+    if usecase_path == "attribute.edit_attributes":
+        element = settings["product"]
+    elif usecase_path == "style.edit_presentation_style":
+        element = settings["style"]
+
     if "Name" not in settings["attributes"]:
         return
-    obj = IfcStore.get_element(settings["product"].id())
+    obj = tool.Ifc.get_object(element)
     if not obj:
         return
     if isinstance(obj, bpy.types.Object):
-        new_name = "{}/{}".format(settings["product"].is_a(), settings["attributes"]["Name"] or "Unnamed")
+        new_name = "{}/{}".format(element.is_a(), settings["attributes"]["Name"] or "Unnamed")
     elif isinstance(obj, bpy.types.Material):
         new_name = settings["attributes"]["Name"] or "Unnamed"
-        if obj.BIMMaterialProperties.ifc_style_id:
-            IfcStore.get_file().by_id(obj.BIMMaterialProperties.ifc_style_id).Name = new_name
-            StyleData.load(IfcStore.get_file(), obj.BIMMaterialProperties.ifc_style_id)
+        material = tool.Ifc.get_entity(obj)
+        if material and material != element:
+            material.Name = new_name
+        style = tool.Style.get_style(obj)
+        if style and style != element:
+            style.Name = new_name
     collection = bpy.data.collections.get(obj.name)
     if collection:
         collection.name = new_name
     obj.name = new_name
+    blenderbim.bim.handler.refresh_ui_data()
diff --git a/src/blenderbim/blenderbim/bim/module/project/operator.py b/src/blenderbim/blenderbim/bim/module/project/operator.py
index 8ae9a03201..f536698149 100644
--- a/src/blenderbim/blenderbim/bim/module/project/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/project/operator.py
@@ -611,10 +611,14 @@ class LinkIfc(bpy.types.Operator):
     bl_description = "Link a Blender file"
     filepath: bpy.props.StringProperty(subtype="FILE_PATH")
     filter_glob: bpy.props.StringProperty(default="*.blend;*.blend1", options={"HIDDEN"})
+    use_relative_path: bpy.props.BoolProperty(name="Use Relative Path", default=False)
 
     def execute(self, context):
         new = context.scene.BIMProjectProperties.links.add()
-        new.name = self.filepath
+        filepath = self.filepath
+        if self.use_relative_path:
+            filepath = os.path.relpath(filepath, bpy.path.abspath("//"))
+        new.name = filepath
         bpy.ops.bim.load_link(filepath=self.filepath)
         return {"FINISHED"}
 
@@ -646,13 +650,16 @@ class UnloadLink(bpy.types.Operator):
     filepath: bpy.props.StringProperty()
 
     def execute(self, context):
+        filepath = self.filepath
+        if not os.path.isabs(filepath):
+            filepath = os.path.abspath(os.path.join(bpy.path.abspath("//"), filepath))
         for collection in context.scene.collection.children:
-            if collection.library and collection.library.filepath == self.filepath:
+            if collection.library and collection.library.filepath == filepath:
                 context.scene.collection.children.unlink(collection)
         for scene in bpy.data.scenes:
-            if scene.library and scene.library.filepath == self.filepath:
+            if scene.library and scene.library.filepath == filepath:
                 bpy.data.scenes.remove(scene)
-        link = context.scene.BIMProjectProperties.links.get(self.filepath)
+        link = context.scene.BIMProjectProperties.links.get(filepath)
         link.is_loaded = False
         return {"FINISHED"}
 
@@ -665,16 +672,19 @@ class LoadLink(bpy.types.Operator):
     filepath: bpy.props.StringProperty()
 
     def execute(self, context):
+        filepath = self.filepath
+        if not os.path.isabs(filepath):
+            filepath = os.path.abspath(os.path.join(bpy.path.abspath("//"), filepath))
         with bpy.data.libraries.load(self.filepath, link=True) as (data_from, data_to):
             data_to.scenes = data_from.scenes
         for scene in bpy.data.scenes:
-            if not scene.library or scene.library.filepath != self.filepath:
+            if not scene.library or scene.library.filepath != filepath:
                 continue
             for child in scene.collection.children:
                 if "IfcProject" not in child.name:
                     continue
                 bpy.data.scenes[0].collection.children.link(child)
-        link = context.scene.BIMProjectProperties.links.get(self.filepath)
+        link = context.scene.BIMProjectProperties.links.get(filepath)
         link.is_loaded = True
         return {"FINISHED"}
 
diff --git a/src/blenderbim/blenderbim/bim/module/project/ui.py b/src/blenderbim/blenderbim/bim/module/project/ui.py
index cd962563d5..271ce2de55 100644
--- a/src/blenderbim/blenderbim/bim/module/project/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/project/ui.py
@@ -284,11 +284,12 @@ class BIM_UL_links(UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
         if item:
             row = layout.row(align=True)
-            row.label(text=item.name)
             if item.is_loaded:
+                row.label(text=item.name)
                 op = row.operator("bim.unload_link", text="", icon="UNLINKED")
                 op.filepath = item.name
             else:
+                row.prop(item, "name", text="")
                 op = row.operator("bim.load_link", text="", icon="LINKED")
                 op.filepath = item.name
                 op = row.operator("bim.unlink_ifc", text="", icon="X")
diff --git a/src/blenderbim/blenderbim/bim/module/root/data.py b/src/blenderbim/blenderbim/bim/module/root/data.py
index 365bd4ac54..9d2ee77ae4 100644
--- a/src/blenderbim/blenderbim/bim/module/root/data.py
+++ b/src/blenderbim/blenderbim/bim/module/root/data.py
@@ -32,12 +32,47 @@ class IfcClassData:
     @classmethod
     def load(cls):
         cls.is_loaded = True
-        cls.data = {
-            "contexts": cls.contexts(),
-            "has_entity": cls.has_entity(),
-            "name": cls.name(),
-            "ifc_class": cls.ifc_class(),
-        }
+        cls.data = {}
+        cls.data["ifc_products"] = cls.ifc_products()
+        cls.data["ifc_classes"] = cls.ifc_classes()
+        cls.data["contexts"] = cls.contexts()
+        cls.data["has_entity"] = cls.has_entity()
+        cls.data["name"] = cls.name()
+        cls.data["ifc_class"] = cls.ifc_class()
+
+    @classmethod
+    def ifc_products(cls):
+        products = [
+            "IfcElement",
+            "IfcElementType",
+            "IfcSpatialElement",
+            "IfcGroup",
+            "IfcStructuralItem",
+            "IfcContext",
+            "IfcAnnotation",
+            "IfcRelSpaceBoundary",
+        ]
+        if tool.Ifc.get_schema() == "IFC2X3":
+            products = [
+                "IfcElement",
+                "IfcElementType",
+                "IfcSpatialStructureElement",
+                "IfcGroup",
+                "IfcStructuralItem",
+                "IfcAnnotation",
+                "IfcRelSpaceBoundary",
+            ]
+        return [(e, e, "") for e in products]
+
+    @classmethod
+    def ifc_classes(cls):
+        ifc_product = bpy.context.scene.BIMRootProperties.ifc_product
+        declaration = tool.Ifc.schema().declaration_by_name(ifc_product)
+        declarations = ifcopenshell.util.schema.get_subtypes(declaration)
+        names = [d.name() for d in declarations]
+        if ifc_product == "IfcElementType":
+            names.extend(("IfcDoorStyle", "IfcWindowStyle"))
+        return [(c, c, "") for c in sorted(names)]
 
     @classmethod
     def contexts(cls):
diff --git a/src/blenderbim/blenderbim/bim/module/root/prop.py b/src/blenderbim/blenderbim/bim/module/root/prop.py
index fd96b0c7cc..8b598a2338 100644
--- a/src/blenderbim/blenderbim/bim/module/root/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/root/prop.py
@@ -33,17 +33,11 @@ from bpy.props import (
     CollectionProperty,
 )
 
-products_enum = []
-classes_enum = []
 types_enum = []
 
 
 def purge():
-    global products_enum
-    global classes_enum
     global types_enum
-    products_enum = []
-    classes_enum = []
     types_enum = []
 
 
@@ -61,10 +55,9 @@ def getIfcPredefinedTypes(self, context):
     return types_enum
 
 
-def refreshClasses(self, context):
-    global classes_enum
-    classes_enum.clear()
-    enum = getIfcClasses(self, context)
+def refresh_classes(self, context):
+    IfcClassData.load()
+    enum = get_ifc_classes(self, context)
     context.scene.BIMRootProperties.ifc_class = enum[0][0]
 
 
@@ -76,38 +69,16 @@ def refreshPredefinedTypes(self, context):
         context.scene.BIMRootProperties.ifc_predefined_type = enum[0][0]
 
 
-def getIfcProducts(self, context):
-    global products_enum
-    file = IfcStore.get_file()
-    if len(products_enum) < 1:
-        products_enum.extend(
-            [
-                (e, e, "")
-                for e in [
-                    "IfcElement",
-                    "IfcElementType",
-                    "IfcSpatialElement",
-                    "IfcGroup",
-                    "IfcStructuralItem",
-                    "IfcContext",
-                    "IfcAnnotation",
-                    "IfcRelSpaceBoundary",
-                ]
-            ]
-        )
-        if file.schema == "IFC2X3":
-            products_enum[2] = ("IfcSpatialStructureElement", "IfcSpatialStructureElement", "")
-    return products_enum
+def get_ifc_products(self, context):
+    if not IfcClassData.is_loaded:
+        IfcClassData.load()
+    return IfcClassData.data["ifc_products"]
 
 
-def getIfcClasses(self, context):
-    global classes_enum
-    file = IfcStore.get_file()
-    if len(classes_enum) < 1 and file:
-        declaration = IfcStore.get_schema().declaration_by_name(context.scene.BIMRootProperties.ifc_product)
-        declarations = ifcopenshell.util.schema.get_subtypes(declaration)
-        classes_enum.extend([(c, c, "") for c in sorted([d.name() for d in declarations])])
-    return classes_enum
+def get_ifc_classes(self, context):
+    if not IfcClassData.is_loaded:
+        IfcClassData.load()
+    return IfcClassData.data["ifc_classes"]
 
 
 def get_contexts(self, context):
@@ -118,7 +89,7 @@ def get_contexts(self, context):
 
 class BIMRootProperties(PropertyGroup):
     contexts: EnumProperty(items=get_contexts, name="Contexts")
-    ifc_product: EnumProperty(items=getIfcProducts, name="Products", update=refreshClasses)
-    ifc_class: EnumProperty(items=getIfcClasses, name="Class", update=refreshPredefinedTypes)
+    ifc_product: EnumProperty(items=get_ifc_products, name="Products", update=refresh_classes)
+    ifc_class: EnumProperty(items=get_ifc_classes, name="Class", update=refreshPredefinedTypes)
     ifc_predefined_type: EnumProperty(items=getIfcPredefinedTypes, name="Predefined Type", default=None)
     ifc_userdefined_type: StringProperty(name="Userdefined Type")
diff --git a/src/blenderbim/blenderbim/bim/module/sequence/operator.py b/src/blenderbim/blenderbim/bim/module/sequence/operator.py
index 7626b001ab..d7082cfa9e 100644
--- a/src/blenderbim/blenderbim/bim/module/sequence/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/sequence/operator.py
@@ -989,6 +989,7 @@ class GenerateGanttChart(bpy.types.Operator):
         data = {
             "pID": task.id(),
             "pName": task.Name,
+            "pCaption": task.Name,
             "pStart": task.TaskTime.ScheduleStart if task.TaskTime else "",
             "pEnd": task.TaskTime.ScheduleFinish if task.TaskTime else "",
             "pPlanStart": task.TaskTime.ScheduleStart if task.TaskTime else "",
@@ -999,6 +1000,7 @@ class GenerateGanttChart(bpy.types.Operator):
             "pParent": task.Nests[0].RelatingObject.id() if task.Nests else 0,
             "pOpen": 1,
             "pCost": 1,
+            "ifcduration": task.TaskTime.ScheduleDuration if task.TaskTime else "",
         }
         if task.TaskTime and task.TaskTime.IsCritical:
             data["pClass"] = "gtaskred"
@@ -1230,7 +1232,7 @@ class ExportMSP(bpy.types.Operator, ImportHelper):
         start = time.time()
         ifc2msp = Ifc2Msp()
         ifc2msp.work_schedule = self.file.by_type("IfcWorkSchedule")[0]
-        ifc2msp.xml = self.filepath
+        ifc2msp.xml = bpy.path.ensure_ext(self.filepath, ".xml")
         ifc2msp.file = self.file
         ifc2msp.holiday_start_date = parser.parse(self.holiday_start_date).date()
         ifc2msp.holiday_finish_date = parser.parse(self.holiday_finish_date).date()
@@ -1259,7 +1261,7 @@ class ExportP6(bpy.types.Operator, ImportHelper):
         self.file = IfcStore.get_file()
         start = time.time()
         ifc2p6 = Ifc2P6()
-        ifc2p6.xml = self.filepath
+        ifc2p6.xml = bpy.path.ensure_ext(self.filepath, ".xml")
         ifc2p6.file = self.file
         ifc2p6.holiday_start_date = parser.parse(self.holiday_start_date).date()
         ifc2p6.holiday_finish_date = parser.parse(self.holiday_finish_date).date()
@@ -1679,6 +1681,10 @@ class EnableEditingSequenceTimeLag(bpy.types.Operator):
 
     def import_attributes(self, name, prop, data):
         if name == "LagValue":
+            prop = self.props.time_lag_attributes.add()
+            prop.name = name
+            prop.is_null = data[name] is None
+            prop.is_optional = False
             if isinstance(data[name], isodate.Duration):
                 prop.data_type = "string"
                 prop.string_value = (
diff --git a/src/blenderbim/blenderbim/bim/module/sequence/prop.py b/src/blenderbim/blenderbim/bim/module/sequence/prop.py
index a923352163..5c3eb6a18f 100644
--- a/src/blenderbim/blenderbim/bim/module/sequence/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/sequence/prop.py
@@ -17,6 +17,7 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import bpy
+import isodate
 import ifcopenshell.api
 import ifcopenshell.util.attribute
 from blenderbim.bim.ifc import IfcStore
@@ -184,6 +185,16 @@ def updateTaskDuration(self, context):
     props = context.scene.BIMWorkScheduleProperties
     if not props.is_task_update_enabled:
         return
+
+    if self.duration == "-":
+        return
+
+    try:
+        isodate.parse_duration(self.duration),
+    except:
+        self.duration = "-"
+        return
+
     self.file = IfcStore.get_file()
     task = self.file.by_id(self.ifc_definition_id)
     if task.TaskTime:
diff --git a/src/blenderbim/blenderbim/bim/module/style/__init__.py b/src/blenderbim/blenderbim/bim/module/style/__init__.py
index 159b919712..c7ecdab9e3 100644
--- a/src/blenderbim/blenderbim/bim/module/style/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/style/__init__.py
@@ -21,22 +21,30 @@ from . import ui, prop, operator
 
 classes = (
     operator.AddStyle,
-    operator.EnableEditingStyle,
     operator.DisableEditingStyle,
+    operator.DisableEditingStyles,
     operator.EditStyle,
+    operator.EnableEditingStyle,
+    operator.LoadStyles,
     operator.RemoveStyle,
+    operator.UnlinkStyle,
     operator.UpdateStyleColours,
     operator.UpdateStyleTextures,
-    operator.UnlinkStyle,
+    prop.Style,
+    prop.BIMStylesProperties,
     prop.BIMStyleProperties,
+    ui.BIM_PT_styles,
     ui.BIM_PT_style,
     ui.BIM_PT_style_attributes,
+    ui.BIM_UL_styles,
 )
 
 
 def register():
+    bpy.types.Scene.BIMStylesProperties = bpy.props.PointerProperty(type=prop.BIMStylesProperties)
     bpy.types.Material.BIMStyleProperties = bpy.props.PointerProperty(type=prop.BIMStyleProperties)
 
 
 def unregister():
+    del bpy.types.Scene.BIMStylesProperties
     del bpy.types.Material.BIMStyleProperties
diff --git a/src/blenderbim/blenderbim/bim/module/style/data.py b/src/blenderbim/blenderbim/bim/module/style/data.py
index 78714b7fcd..9f6d768785 100644
--- a/src/blenderbim/blenderbim/bim/module/style/data.py
+++ b/src/blenderbim/blenderbim/bim/module/style/data.py
@@ -18,12 +18,33 @@
 
 import bpy
 import blenderbim.tool as tool
+import ifcopenshell
 
 
 def refresh():
+    StylesData.is_loaded = False
     StyleAttributesData.is_loaded = False
 
 
+class StylesData:
+    data = {}
+    is_loaded = False
+
+    @classmethod
+    def load(cls):
+        cls.data = {"style_types": cls.style_types(), "total_styles": cls.total_styles()}
+
+    @classmethod
+    def style_types(cls):
+        declaration = tool.Ifc.schema().declaration_by_name("IfcPresentationStyle")
+        declarations = ifcopenshell.util.schema.get_subtypes(declaration)
+        return [(c, c, "") for c in sorted([d.name() for d in declarations])]
+
+    @classmethod
+    def total_styles(cls):
+        return len(tool.Ifc.get().by_type("IfcPresentationStyle"))
+
+
 class StyleAttributesData:
     data = {}
     is_loaded = False
diff --git a/src/blenderbim/blenderbim/bim/module/style/operator.py b/src/blenderbim/blenderbim/bim/module/style/operator.py
index 174f7e16d5..0e352ed138 100644
--- a/src/blenderbim/blenderbim/bim/module/style/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/style/operator.py
@@ -59,9 +59,10 @@ class RemoveStyle(bpy.types.Operator, Operator):
     bl_idname = "bim.remove_style"
     bl_label = "Remove Style"
     bl_options = {"REGISTER", "UNDO"}
+    style: bpy.props.IntProperty()
 
     def _execute(self, context):
-        core.remove_style(tool.Ifc, tool.Style, obj=context.active_object.active_material)
+        core.remove_style(tool.Ifc, tool.Material, tool.Style, style=tool.Ifc.get().by_id(self.style))
 
 
 class AddStyle(bpy.types.Operator, Operator):
@@ -107,3 +108,22 @@ class EditStyle(bpy.types.Operator, Operator):
 
     def _execute(self, context):
         core.edit_style(tool.Ifc, tool.Style, obj=context.active_object.active_material)
+
+
+class DisableEditingStyles(bpy.types.Operator, Operator):
+    bl_idname = "bim.disable_editing_styles"
+    bl_options = {"REGISTER", "UNDO"}
+    bl_label = "Disable Editing Styles"
+
+    def _execute(self, context):
+        core.disable_editing_styles(tool.Style)
+
+
+class LoadStyles(bpy.types.Operator, Operator):
+    bl_idname = "bim.load_styles"
+    bl_label = "Load Styles"
+    bl_options = {"REGISTER", "UNDO"}
+    style_type: bpy.props.StringProperty()
+
+    def _execute(self, context):
+        core.load_styles(tool.Style, style_type=self.style_type)
diff --git a/src/blenderbim/blenderbim/bim/module/style/prop.py b/src/blenderbim/blenderbim/bim/module/style/prop.py
index b5ae846627..f8666f8793 100644
--- a/src/blenderbim/blenderbim/bim/module/style/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/style/prop.py
@@ -19,6 +19,7 @@
 import bpy
 from blenderbim.bim.ifc import IfcStore
 from blenderbim.bim.prop import StrProperty, Attribute
+from blenderbim.bim.module.style.data import StylesData
 from bpy.types import PropertyGroup
 from bpy.props import (
     PointerProperty,
@@ -32,6 +33,25 @@ from bpy.props import (
 )
 
 
+def get_style_types(self, context):
+    if not StylesData.is_loaded:
+        StylesData.load()
+    return StylesData.data["style_types"]
+
+
+class Style(PropertyGroup):
+    name: StringProperty(name="Name")
+    ifc_definition_id: IntProperty(name="IFC Definition ID")
+    total_elements: IntProperty(name="Total Elements")
+
+
+class BIMStylesProperties(PropertyGroup):
+    is_editing: BoolProperty(name="Is Editing")
+    style_type: EnumProperty(items=get_style_types, name="Style Type")
+    styles: CollectionProperty(name="Styles", type=Style)
+    active_style_index: IntProperty(name="Active Style Index")
+
+
 class BIMStyleProperties(PropertyGroup):
     attributes: CollectionProperty(name="Attributes", type=Attribute)
     is_editing: BoolProperty(name="Is Editing")
diff --git a/src/blenderbim/blenderbim/bim/module/style/ui.py b/src/blenderbim/blenderbim/bim/module/style/ui.py
index abd2ce812c..d41a3ad46f 100644
--- a/src/blenderbim/blenderbim/bim/module/style/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/style/ui.py
@@ -17,9 +17,51 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import blenderbim.bim.helper
-from bpy.types import Panel
+from bpy.types import Panel, UIList
 from blenderbim.bim.ifc import IfcStore
-from blenderbim.bim.module.style.data import StyleAttributesData
+from blenderbim.bim.module.style.data import StylesData, StyleAttributesData
+
+
+class BIM_PT_styles(Panel):
+    bl_label = "IFC Styles"
+    bl_idname = "BIM_PT_styles"
+    bl_options = {"DEFAULT_CLOSED"}
+    bl_space_type = "PROPERTIES"
+    bl_region_type = "WINDOW"
+    bl_context = "scene"
+    bl_parent_id = "BIM_PT_geometry"
+
+    @classmethod
+    def poll(cls, context):
+        return IfcStore.get_file()
+
+    def draw(self, context):
+        if not StylesData.is_loaded:
+            StylesData.load()
+
+        self.props = context.scene.BIMStylesProperties
+
+        row = self.layout.row(align=True)
+        row.label(text="{} Styles Found".format(StylesData.data["total_styles"]), icon="MATERIAL")
+        row = self.layout.row(align=True)
+        if self.props.is_editing:
+            row.operator("bim.disable_editing_styles", text="", icon="CANCEL")
+        else:
+            row.prop(self.props, "style_type", text="")
+            row.operator("bim.load_styles", text="", icon="IMPORT").style_type = self.props.style_type
+            return
+
+        row = self.layout.row(align=True)
+        row.alignment = "RIGHT"
+
+        #row.operator("bim.add_presentation_style", text="", icon="ADD")
+        if self.props.styles and self.props.active_style_index < len(self.props.styles):
+            style = self.props.styles[self.props.active_style_index]
+        #    op = row.operator("bim.select_by_style", text="", icon="RESTRICT_SELECT_OFF")
+        #    op.style = style.ifc_definition_id
+            row.operator("bim.remove_style", text="", icon="X").style = style.ifc_definition_id
+
+        self.layout.template_list("BIM_UL_styles", "", self.props, "styles", self.props, "active_style_index")
 
 
 class BIM_PT_style(Panel):
@@ -44,7 +86,7 @@ class BIM_PT_style(Panel):
             row.operator("bim.update_style_colours", icon="GREASEPENCIL")
             row.operator("bim.update_style_textures", icon="TEXTURE", text="")
             row.operator("bim.unlink_style", icon="UNLINKED", text="")
-            row.operator("bim.remove_style", icon="X", text="")
+            row.operator("bim.remove_style", icon="X", text="").style = props.ifc_style_id
         else:
             row.operator("bim.add_style", icon="ADD")
 
@@ -89,3 +131,13 @@ class BIM_PT_style_attributes(Panel):
                 row = self.layout.row(align=True)
                 row.label(text=attribute["name"])
                 row.label(text=attribute["value"])
+
+
+class BIM_UL_styles(UIList):
+    def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
+        if item:
+            row = layout.row(align=True)
+            row.label(text=item.name)
+            #row2 = row.row()
+            #row2.alignment = "RIGHT"
+            #row2.label(text=str(item.total_elements))
diff --git a/src/blenderbim/blenderbim/bim/module/unit/__init__.py b/src/blenderbim/blenderbim/bim/module/unit/__init__.py
index 11f5ab1395..3eab1de36b 100644
--- a/src/blenderbim/blenderbim/bim/module/unit/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/unit/__init__.py
@@ -20,18 +20,19 @@ import bpy
 from . import ui, prop, operator
 
 classes = (
-    operator.AssignSceneUnits,
-    operator.AssignUnit,
-    operator.UnassignUnit,
-    operator.LoadUnits,
-    operator.DisableUnitEditingUI,
-    operator.RemoveUnit,
+    operator.AddContextDependentUnit,
+    operator.AddConversionBasedUnit,
     operator.AddMonetaryUnit,
     operator.AddSIUnit,
-    operator.AddContextDependentUnit,
-    operator.EnableEditingUnit,
+    operator.AssignSceneUnits,
+    operator.AssignUnit,
     operator.DisableEditingUnit,
+    operator.DisableUnitEditingUI,
     operator.EditUnit,
+    operator.EnableEditingUnit,
+    operator.LoadUnits,
+    operator.RemoveUnit,
+    operator.UnassignUnit,
     prop.Unit,
     prop.BIMUnitProperties,
     ui.BIM_PT_units,
diff --git a/src/blenderbim/blenderbim/bim/module/unit/data.py b/src/blenderbim/blenderbim/bim/module/unit/data.py
index 1111ed0dfa..971e57b03a 100644
--- a/src/blenderbim/blenderbim/bim/module/unit/data.py
+++ b/src/blenderbim/blenderbim/bim/module/unit/data.py
@@ -16,6 +16,10 @@
 # You should have received a copy of the GNU General Public License
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
+import ifcopenshell
+import ifcopenshell.util.unit
+import ifcopenshell.util.schema
+import ifcopenshell.util.attribute
 import blenderbim.tool as tool
 
 
@@ -29,9 +33,32 @@ class UnitsData:
 
     @classmethod
     def load(cls):
-        cls.data = {"total_units": cls.get_total_units()}
+        cls.data = {
+            "unit_classes": cls.unit_classes(),
+            "named_unit_types": cls.named_unit_types(),
+            "conversion_unit_types": cls.conversion_unit_types(),
+            "total_units": cls.get_total_units()
+        }
         cls.is_loaded = True
 
+    @classmethod
+    def unit_classes(cls):
+        declarations = ifcopenshell.util.schema.get_subtypes(tool.Ifc.schema().declaration_by_name("IfcNamedUnit"))
+        results = [(c, c, "") for c in sorted([d.name() for d in declarations])]
+        results.extend([("IfcDerivedUnit", "IfcDerivedUnit", ""), ("IfcMonetaryUnit", "IfcMonetaryUnit", "")])
+        return results
+
+    @classmethod
+    def named_unit_types(cls):
+        values = ifcopenshell.util.attribute.get_enum_items(
+            tool.Ifc.schema().declaration_by_name("IfcNamedUnit").all_attributes()[1]
+        )
+        return [(c, c, "") for c in sorted(values)]
+
+    @classmethod
+    def conversion_unit_types(cls):
+        return [(u, u, "") for u in ifcopenshell.util.unit.si_conversions.keys()]
+
     @classmethod
     def get_total_units(cls):
         ifc = tool.Ifc.get()
diff --git a/src/blenderbim/blenderbim/bim/module/unit/operator.py b/src/blenderbim/blenderbim/bim/module/unit/operator.py
index 580a3d06f9..9eb56a31fc 100644
--- a/src/blenderbim/blenderbim/bim/module/unit/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/unit/operator.py
@@ -94,6 +94,16 @@ class RemoveUnit(bpy.types.Operator, Operator):
         core.remove_unit(tool.Ifc, tool.Unit, unit=tool.Ifc.get().by_id(self.unit))
 
 
+class AddConversionBasedUnit(bpy.types.Operator, Operator):
+    bl_idname = "bim.add_conversion_based_unit"
+    bl_label = "Add Conversion Based Unit"
+    bl_options = {"REGISTER", "UNDO"}
+    name: bpy.props.StringProperty()
+
+    def _execute(self, context):
+        core.add_conversion_based_unit(tool.Ifc, tool.Unit, name=self.name)
+
+
 class AddMonetaryUnit(bpy.types.Operator, Operator):
     bl_idname = "bim.add_monetary_unit"
     bl_label = "Add Monetary Unit"
diff --git a/src/blenderbim/blenderbim/bim/module/unit/prop.py b/src/blenderbim/blenderbim/bim/module/unit/prop.py
index 46fa36c9ca..22ef9c7a0e 100644
--- a/src/blenderbim/blenderbim/bim/module/unit/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/unit/prop.py
@@ -17,11 +17,9 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import bpy
-import ifcopenshell
-import ifcopenshell.util.schema
-import ifcopenshell.util.attribute
 from blenderbim.bim.ifc import IfcStore
 from blenderbim.bim.prop import StrProperty, Attribute
+from blenderbim.bim.module.unit.data import UnitsData
 from bpy.types import PropertyGroup
 from bpy.props import (
     PointerProperty,
@@ -35,34 +33,22 @@ from bpy.props import (
 )
 
 
-unitclasses_enum = []
-namedunittypes_enum = []
+def get_unit_classes(self, context):
+    if not UnitsData.is_loaded:
+        UnitsData.load()
+    return UnitsData.data["unit_classes"]
 
 
-def purge():
-    global unitclasses_enum
-    global namedunittypes_enum
-    unitclasses_enum = []
-    namedunittypes_enum = []
+def get_conversion_unit_types(self, context):
+    if not UnitsData.is_loaded:
+        UnitsData.load()
+    return UnitsData.data["conversion_unit_types"]
 
 
-def getUnitClasses(self, context):
-    global unitclasses_enum
-    if not len(unitclasses_enum) and IfcStore.get_file():
-        declarations = ifcopenshell.util.schema.get_subtypes(IfcStore.get_schema().declaration_by_name("IfcNamedUnit"))
-        unitclasses_enum.extend([(c, c, "") for c in sorted([d.name() for d in declarations])])
-        unitclasses_enum.extend([("IfcDerivedUnit", "IfcDerivedUnit", ""), ("IfcMonetaryUnit", "IfcMonetaryUnit", "")])
-    return unitclasses_enum
-
-
-def getNamedUnitTypes(self, context):
-    global namedunittypes_enum
-    if not len(namedunittypes_enum) and IfcStore.get_file():
-        values = ifcopenshell.util.attribute.get_enum_items(
-            IfcStore.get_schema().declaration_by_name("IfcNamedUnit").all_attributes()[1]
-        )
-        namedunittypes_enum.extend([(c, c, "") for c in sorted(values)])
-    return namedunittypes_enum
+def get_named_unit_types(self, context):
+    if not UnitsData.is_loaded:
+        UnitsData.load()
+    return UnitsData.data["named_unit_types"]
 
 
 class Unit(PropertyGroup):
@@ -78,6 +64,7 @@ class BIMUnitProperties(PropertyGroup):
     units: CollectionProperty(name="Units", type=Unit)
     active_unit_index: IntProperty(name="Active Unit Index")
     active_unit_id: IntProperty(name="Active Unit Id")
-    unit_classes: EnumProperty(items=getUnitClasses, name="Unit Classes")
-    named_unit_types: EnumProperty(items=getNamedUnitTypes, name="Named Unit Types")
+    unit_classes: EnumProperty(items=get_unit_classes, name="Unit Classes")
+    conversion_unit_types: EnumProperty(items=get_conversion_unit_types, name="Conversion Unit Types")
+    named_unit_types: EnumProperty(items=get_named_unit_types, name="Named Unit Types")
     unit_attributes: CollectionProperty(name="Unit Attributes", type=Attribute)
diff --git a/src/blenderbim/blenderbim/bim/module/unit/ui.py b/src/blenderbim/blenderbim/bim/module/unit/ui.py
index 75a4b5175d..8f053d108b 100644
--- a/src/blenderbim/blenderbim/bim/module/unit/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/unit/ui.py
@@ -57,6 +57,10 @@ class BIM_PT_units(Panel):
 
         if self.props.unit_classes == "IfcMonetaryUnit":
             row.operator("bim.add_monetary_unit", text="", icon="ADD")
+        elif self.props.unit_classes in ("IfcConversionBasedUnit", "IfcConversionBasedUnitWithOffset"):
+            row.prop(self.props, "conversion_unit_types", text="")
+            op = row.operator("bim.add_conversion_based_unit", text="", icon="ADD")
+            op.name = self.props.conversion_unit_types
         elif self.props.unit_classes == "IfcDerivedUnit":
             pass  # TODO
         elif self.props.unit_classes == "IfcSIUnit":
diff --git a/src/blenderbim/blenderbim/bim/module/void/operator.py b/src/blenderbim/blenderbim/bim/module/void/operator.py
index 7e5edb1d38..079bf72c97 100644
--- a/src/blenderbim/blenderbim/bim/module/void/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/void/operator.py
@@ -44,6 +44,7 @@ class AddOpening(bpy.types.Operator):
         if not element_id:
             return {"FINISHED"}
         element = self.file.by_id(element_id)
+        tool.Geometry.clear_cache(element)
         if element.is_a("IfcOpeningElement"):
             self.report({"WARNING"}, "An IfcOpeningElement can't be voided")
             return {"FINISHED"}
@@ -132,6 +133,7 @@ class RemoveOpening(bpy.types.Operator):
                 should_sync_changes_first=False,
             )
 
+        tool.Geometry.clear_cache(tool.Ifc.get_entity(obj))
         Data.load(IfcStore.get_file(), obj.BIMObjectProperties.ifc_definition_id)
         return {"FINISHED"}
 
diff --git a/src/blenderbim/blenderbim/bim/module/void/ui.py b/src/blenderbim/blenderbim/bim/module/void/ui.py
index a1bac98af7..c17e1922ed 100644
--- a/src/blenderbim/blenderbim/bim/module/void/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/void/ui.py
@@ -49,7 +49,11 @@ class BIM_PT_voids(Panel):
         if len(context.selected_objects) == 2:
             op = row.operator("bim.add_opening", icon="ADD", text="Add Opening")
             for obj in context.selected_objects:
-                if "IfcOpeningElement" in obj.name or not obj.BIMObjectProperties.ifc_definition_id:
+                if (
+                    "IfcOpeningElement" in obj.name
+                    or "IfcOpeningStandardCase" in obj.name
+                    or not obj.BIMObjectProperties.ifc_definition_id
+                ):
                     op.opening = obj.name
                 elif len(obj.children) == 1 and not obj.children[0].BIMObjectProperties.ifc_definition_id:
                     op.opening = obj.children[0].name
diff --git a/src/blenderbim/blenderbim/bim/operator.py b/src/blenderbim/blenderbim/bim/operator.py
index 087a6dcede..7b171961e0 100644
--- a/src/blenderbim/blenderbim/bim/operator.py
+++ b/src/blenderbim/blenderbim/bim/operator.py
@@ -22,6 +22,7 @@ import json
 import webbrowser
 import ifcopenshell
 import blenderbim.bim.handler
+import blenderbim.tool as tool
 from . import schema
 from blenderbim.bim.ifc import IfcStore
 from blenderbim.bim.ui import IFCFileSelector
@@ -39,6 +40,43 @@ class OpenUri(bpy.types.Operator):
         return {"FINISHED"}
 
 
+class SelectURIAttribute(bpy.types.Operator):
+    bl_idname = "bim.select_uri_attribute"
+    bl_label = "Select URI Attribute"
+    bl_options = {"REGISTER", "UNDO"}
+    bl_description = "Select a local file"
+    filepath: bpy.props.StringProperty(subtype="FILE_PATH")
+    data_path: bpy.props.StringProperty(name="Data Path")
+    use_relative_path: bpy.props.BoolProperty(name="Use Relative Path", default=False)
+
+    def execute(self, context):
+        # data_path contains the latter half of the path to the string_value property
+        # I have no idea how to find out the former half, so let's just use brute force.
+        data_path = self.data_path.replace(".string_value", "")
+        attribute = None
+        try:
+            attribute = eval(f"bpy.context.scene.{data_path}")
+        except:
+            try:
+                attribute = eval(f"bpy.context.active_object.{data_path}")
+            except:
+                try:
+                    attribute = eval(f"bpy.context.active_object.active_material.{data_path}")
+                except:
+                    # Do you know a better way?
+                    pass
+        if attribute:
+            filepath = self.filepath
+            if self.use_relative_path:
+                filepath = os.path.relpath(filepath, os.path.dirname(tool.Ifc.get_path()))
+            attribute.string_value = filepath
+        return {"FINISHED"}
+
+    def invoke(self, context, event):
+        context.window_manager.fileselect_add(self)
+        return {"RUNNING_MODAL"}
+
+
 class SelectIfcFile(bpy.types.Operator, IFCFileSelector):
     bl_idname = "bim.select_ifc_file"
     bl_label = "Select IFC File"
diff --git a/src/blenderbim/blenderbim/bim/prop.py b/src/blenderbim/blenderbim/bim/prop.py
index 06af23d2e4..50817c4487 100644
--- a/src/blenderbim/blenderbim/bim/prop.py
+++ b/src/blenderbim/blenderbim/bim/prop.py
@@ -190,10 +190,11 @@ class Attribute(PropertyGroup):
     bool_value: BoolProperty(name="Value", update=updateAttributeValue)
     int_value: IntProperty(name="Value", update=updateAttributeValue)
     float_value: FloatProperty(name="Value", update=updateAttributeValue)
-    is_null: BoolProperty(name="Is Null")
-    is_optional: BoolProperty(name="Is Optional")
     enum_items: StringProperty(name="Value")
     enum_value: EnumProperty(items=getAttributeEnumValues, name="Value", update=updateAttributeValue)
+    is_null: BoolProperty(name="Is Null")
+    is_optional: BoolProperty(name="Is Optional")
+    is_uri: BoolProperty(name="Is Uri", default=False)
 
     def get_value(self):
         if self.is_null:
diff --git a/src/blenderbim/blenderbim/bim/ui.py b/src/blenderbim/blenderbim/bim/ui.py
index 83b2ba536d..000ceac13c 100644
--- a/src/blenderbim/blenderbim/bim/ui.py
+++ b/src/blenderbim/blenderbim/bim/ui.py
@@ -233,7 +233,7 @@ class BIM_PT_geometry(Panel):
 
 
 class BIM_PT_4D5D(Panel):
-    bl_label = "IFC 4D/5D"
+    bl_label = "IFC Costing and Scheduling"
     bl_space_type = "PROPERTIES"
     bl_region_type = "WINDOW"
     bl_context = "scene"
diff --git a/src/blenderbim/blenderbim/core/document.py b/src/blenderbim/blenderbim/core/document.py
index d9e2fa22b1..ce6dc374c6 100644
--- a/src/blenderbim/blenderbim/core/document.py
+++ b/src/blenderbim/blenderbim/core/document.py
@@ -17,16 +17,31 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 
-def load_information(document):
-    document.import_information()
-    document.enable_information_editing_ui()
-    document.disable_editing_document()
+def load_project_documents(document):
+    document.clear_document_tree()
+    document.import_project_documents()
+    document.clear_breadcrumbs()
+    document.enable_editing_ui()
 
 
-def load_references(document):
-    document.import_references()
-    document.enable_reference_editing_ui()
-    document.disable_editing_document()
+def load_document(document_tool, document=None):
+    document_tool.clear_document_tree()
+    document_tool.import_subdocuments(document)
+    document_tool.import_references(document)
+    document_tool.disable_editing_document()
+    document_tool.add_breadcrumb(document)
+
+
+def load_parent_document(document):
+    document.clear_document_tree()
+    document.remove_latest_breadcrumb()
+    parent = document.get_active_breadcrumb()
+    if parent:
+        document.import_subdocuments(parent)
+        document.import_references(parent)
+        document.disable_editing_document()
+    else:
+        document.import_project_documents()
 
 
 def disable_document_editing_ui(document):
@@ -44,52 +59,53 @@ def disable_editing_document(document):
 
 
 def add_information(ifc, document):
-    result = ifc.run("document.add_information")
-    document.import_information()
-    document.import_document_attributes(result)
-    document.set_active_document(result)
+    document.clear_document_tree()
+    parent = document.get_active_breadcrumb()
+    information = ifc.run("document.add_information", parent=parent)
+    ifc.run("document.add_reference", information=information)
+    if parent:
+        document.import_subdocuments(parent)
+        document.import_references(parent)
+    else:
+        document.import_project_documents()
 
 
 def add_reference(ifc, document):
-    result = ifc.run("document.add_reference")
-    document.import_references()
-    document.import_document_attributes(result)
-    document.set_active_document(result)
+    parent = document.get_active_breadcrumb()
+    ifc.run("document.add_reference", information=parent)
+    document.clear_document_tree()
+    document.import_subdocuments(parent)
+    document.import_references(parent)
 
 
-def edit_information(ifc, document, information=None):
-    attributes = document.export_document_attributes()
-    ifc.run("document.edit_information", information=information, attributes=attributes)
-    document.disable_editing_document()
-    document.import_information()
-
-
-def edit_reference(ifc, document, reference=None):
-    attributes = document.export_document_attributes()
-    ifc.run("document.edit_reference", reference=reference, attributes=attributes)
-    document.disable_editing_document()
-    document.import_references()
+def edit_document(ifc, document_tool, document=None):
+    attributes = document_tool.export_document_attributes()
+    if document_tool.is_document_information(document):
+        ifc.run("document.edit_information", information=document, attributes=attributes)
+    else:
+        ifc.run("document.edit_reference", reference=document, attributes=attributes)
+    document_tool.disable_editing_document()
+    document_tool.clear_document_tree()
+    parent = document_tool.get_active_breadcrumb()
+    if parent:
+        document_tool.import_subdocuments(parent)
+        document_tool.import_references(parent)
+    else:
+        document_tool.import_project_documents()
 
 
 def remove_document(ifc, document_tool, document=None):
+    document_tool.clear_document_tree()
     if document_tool.is_document_information(document):
-        ifc.run("document.remove_document", document=document)
-        document_tool.import_information()
+        ifc.run("document.remove_information", information=document)
     else:
-        ifc.run("document.remove_document", document=document)
-        document_tool.import_references()
-    document_tool.disable_editing_document()
-
-
-def enable_assigning_document(document, obj=None):
-    document.import_references()
-    document.enable_reference_editing_ui()
-    document.disable_editing_document()
-    document.enable_document_assignment_ui(obj)
-
-
-def disable_assigning_document(document, obj=None):
-    document.disable_document_assignment_ui(obj)
+        ifc.run("document.remove_reference", reference=document)
+    parent = document_tool.get_active_breadcrumb()
+    if parent:
+        document_tool.import_subdocuments(parent)
+        document_tool.import_references(parent)
+    else:
+        document_tool.import_project_documents()
 
 
 def assign_document(ifc, product=None, document=None):
diff --git a/src/blenderbim/blenderbim/core/drawing.py b/src/blenderbim/blenderbim/core/drawing.py
index 28a228c1b0..ac43fd3323 100644
--- a/src/blenderbim/blenderbim/core/drawing.py
+++ b/src/blenderbim/blenderbim/core/drawing.py
@@ -85,7 +85,7 @@ def open_sheet(drawing, sheet=None):
 
 
 def remove_sheet(ifc, drawing, sheet=None):
-    ifc.run("document.remove_document", document=sheet)
+    ifc.run("document.remove_information", information=sheet)
     drawing.import_sheets()
 
 
@@ -99,7 +99,7 @@ def disable_editing_drawings(drawing):
 
 
 def add_drawing(ifc, collector, drawing, target_view=None, location_hint=None):
-    drawing_name = drawing.ensure_unique_drawing_name("UNTITLED")
+    drawing_name = drawing.ensure_unique_drawing_name(drawing.generate_drawing_name(target_view, location_hint))
     drawing_matrix = drawing.generate_drawing_matrix(target_view, location_hint)
     camera = drawing.create_camera(drawing_name, drawing_matrix)
     element = drawing.run_root_assign_class(
@@ -158,3 +158,48 @@ def add_annotation(ifc, collector, drawing_tool, drawing=None, object_type=None)
         ifc.run("group.assign_group", group=drawing_tool.get_drawing_group(drawing), product=element)
     collector.assign(obj)
     drawing_tool.enable_editing(obj)
+
+
+def sync_references(ifc, collector, drawing_tool, drawing=None):
+    context = drawing_tool.get_annotation_context(drawing_tool.get_drawing_target_view(drawing))
+    if not context:
+        return
+
+    group = drawing_tool.get_drawing_group(drawing)
+    for reference_element in drawing_tool.get_potential_reference_elements(drawing):
+        reference_obj = ifc.get_object(reference_element)
+        annotation = drawing_tool.get_drawing_reference_annotation(drawing, reference_element)
+
+        should_delete_existing_annotation = False
+        should_create_annotation = False
+
+        if annotation and (
+            not reference_obj
+            or ifc.is_moved(reference_obj)
+            or ifc.is_edited(reference_obj)
+            or ifc.is_deleted(reference_element)
+            or ifc.is_deleted(annotation)
+        ):
+            should_delete_existing_annotation = True
+
+        if reference_obj and (should_delete_existing_annotation or not annotation):
+            should_create_annotation = True
+
+        if should_delete_existing_annotation:
+            annotation_obj = ifc.get_object(annotation)
+            if annotation_obj:
+                drawing_tool.delete_object(annotation_obj)
+            ifc.run("root.remove_product", product=annotation)
+
+        if should_create_annotation:
+            annotation = drawing_tool.generate_reference_annotation(drawing, reference_element, context)
+            if annotation:
+                ifc.run("drawing.assign_product", relating_product=reference_element, related_object=annotation)
+                ifc.run("group.assign_group", group=group, product=annotation)
+                collector.assign(ifc.get_object(annotation))
+
+        if reference_obj and ifc.is_moved(reference_obj):
+            drawing_tool.sync_object_placement(reference_obj)
+
+        if reference_obj and ifc.is_edited(reference_obj):
+            drawing_tool.sync_object_representation(reference_obj)
diff --git a/src/blenderbim/blenderbim/core/material.py b/src/blenderbim/blenderbim/core/material.py
index 88c6405e2b..e0835f92f8 100644
--- a/src/blenderbim/blenderbim/core/material.py
+++ b/src/blenderbim/blenderbim/core/material.py
@@ -21,7 +21,52 @@ def unlink_material(ifc, obj=None):
     ifc.unlink(obj=obj)
 
 
-def add_default_material(ifc, material):
-    obj = material.add_default_material_object()
-    ifc.link(ifc.run("material.add_material", name="Default"), obj)
-    return obj
+def add_material(ifc, material, style, obj=None):
+    if not obj:
+        obj = material.add_default_material_object()
+    ifc_material = ifc.run("material.add_material", name=material.get_name(obj))
+    ifc.link(ifc_material, obj)
+    ifc_style = style.get_style(obj)
+    if ifc_style:
+        context = style.get_context(obj)
+        if context:
+            ifc.run("style.assign_material_style", material=ifc_material, style=ifc_style, context=context)
+    if material.is_editing_materials():
+        material.import_material_definitions(material.get_active_material_type())
+    return ifc_material
+
+
+def add_material_set(ifc, material, set_type=None):
+    ifc_material = ifc.run("material.add_material_set", name="Unnamed", set_type=set_type)
+    if material.is_editing_materials():
+        material.import_material_definitions(material.get_active_material_type())
+    return ifc_material
+
+
+def remove_material(ifc, material_tool, style, material=None):
+    obj = ifc.get_object(material)
+    ifc.unlink(element=material)
+    ifc.run("material.remove_material", material=material)
+    if obj and not style.get_style(obj):
+        material_tool.delete_object(obj)
+    if material_tool.is_editing_materials():
+        material_tool.import_material_definitions(material_tool.get_active_material_type())
+
+
+def remove_material_set(ifc, material_tool, material=None):
+    ifc.run("material.remove_material_set", material=material)
+    if material_tool.is_editing_materials():
+        material_tool.import_material_definitions(material_tool.get_active_material_type())
+
+
+def load_materials(material, material_type=None):
+    material.import_material_definitions(material_type)
+    material.enable_editing_materials()
+
+
+def disable_editing_materials(material):
+    material.disable_editing_materials()
+
+
+def select_by_material(material_tool, material=None):
+    material_tool.select_elements(material_tool.get_elements_by_material(material))
diff --git a/src/blenderbim/blenderbim/core/style.py b/src/blenderbim/blenderbim/core/style.py
index e3a26dfc65..4cc8e32a01 100644
--- a/src/blenderbim/blenderbim/core/style.py
+++ b/src/blenderbim/blenderbim/core/style.py
@@ -33,10 +33,14 @@ def add_style(ifc, style, obj=None):
     return element
 
 
-def remove_style(ifc, style, obj=None):
-    element = style.get_style(obj)
-    ifc.unlink(obj=obj, element=element)
-    ifc.run("style.remove_style", style=element)
+def remove_style(ifc, material, style_tool, style=None):
+    obj = ifc.get_object(style)
+    ifc.unlink(obj=obj, element=style)
+    ifc.run("style.remove_style", style=style)
+    if obj and not ifc.get_entity(obj):
+        material.delete_object(obj)
+    if style_tool.is_editing_styles():
+        style_tool.import_presentation_styles(style_tool.get_active_style_type())
 
 
 def update_style_colours(ifc, style, obj=None):
@@ -97,3 +101,12 @@ def edit_style(ifc, style, obj=None):
     attributes = style.export_surface_attributes(obj)
     ifc.run("style.edit_presentation_style", style=style.get_style(obj), attributes=attributes)
     style.disable_editing(obj)
+
+
+def load_styles(style, style_type=None):
+    style.import_presentation_styles(style_type)
+    style.enable_editing_styles()
+
+
+def disable_editing_styles(style):
+    style.disable_editing_styles()
diff --git a/src/blenderbim/blenderbim/core/tool.py b/src/blenderbim/blenderbim/core/tool.py
index 0ba921fbfa..a77f6cb006 100644
--- a/src/blenderbim/blenderbim/core/tool.py
+++ b/src/blenderbim/blenderbim/core/tool.py
@@ -133,6 +133,25 @@ class Debug:
     def purge_hdf5_cache(cls): pass
 
 
+@interface
+class Document:
+    def add_breadcrumb(cls, document): pass
+    def clear_breadcrumbs(cls): pass
+    def clear_document_tree(cls): pass
+    def disable_editing_document(cls): pass
+    def disable_editing_ui(cls): pass
+    def enable_editing_ui(cls): pass
+    def export_document_attributes(cls): pass
+    def get_active_breadcrumb(cls): pass
+    def import_document_attributes(cls, document): pass
+    def import_project_documents(cls): pass
+    def import_references(cls, document): pass
+    def import_subdocuments(cls, document): pass
+    def is_document_information(cls, document): pass
+    def remove_latest_breadcrumb(cls): pass
+    def set_active_document(cls, document): pass
+
+
 @interface
 class Drawing:
     def create_annotation_object(cls, object_type): pass
@@ -140,6 +159,7 @@ class Drawing:
     def create_svg_sheet(cls, document, titleblock): pass
     def delete_collection(cls, collection): pass
     def delete_drawing_elements(cls, elements): pass
+    def delete_object(cls, obj): pass
     def disable_editing_drawings(cls): pass
     def disable_editing_sheets(cls): pass
     def disable_editing_text(cls, obj): pass
@@ -153,6 +173,7 @@ class Drawing:
     def ensure_unique_identification(cls, identification): pass
     def export_text_literal_attributes(cls, obj): pass
     def generate_drawing_matrix(cls, target_view, location_hint): pass
+    def generate_drawing_name(cls, target_view, location_hint): pass
     def generate_sheet_identification(cls): pass
     def get_annotation_context(cls, target_view): pass
     def get_body_context(cls): pass
@@ -173,6 +194,7 @@ class Drawing:
     def run_root_assign_class(cls, obj=None, ifc_class=None, predefined_type=None, should_add_representation=True, context=None, ifc_representation_class=None): pass
     def set_drawing_collection_name(cls, group, collection): pass
     def show_decorations(cls): pass
+    def sync_object_placement(cls, obj): pass
     def update_text_value(cls, obj): pass
 
 
@@ -227,6 +249,9 @@ class Ifc:
     def get_entity(cls, obj): pass
     def get_object(cls, entity): pass
     def get_schema(cls): pass
+    def is_deleted(cls, element): pass
+    def is_edited(cls, obj): pass
+    def is_moved(cls, obj): pass
     def link(cls, element, obj): pass
     def run(cls, command, **kwargs): pass
     def set(cls, ifc): pass
@@ -251,6 +276,15 @@ class Library:
 @interface
 class Material:
     def add_default_material_object(cls): pass
+    def delete_object(cls, obj): pass
+    def disable_editing_materials(cls): pass
+    def enable_editing_materials(cls): pass
+    def get_active_material_type(cls): pass
+    def get_elements_by_material(cls, material): pass
+    def get_name(cls, obj): pass
+    def import_material_definitions(cls, material_type): pass
+    def is_editing_materials(cls): pass
+    def select_elements(cls, elements): pass
 
 
 @interface
@@ -398,8 +432,11 @@ class Structural:
 class Style:
     def can_support_rendering_style(cls, obj): pass
     def disable_editing(cls, obj): pass
+    def disable_editing_styles(cls): pass
     def enable_editing(cls, obj): pass
+    def enable_editing_styles(cls): pass
     def export_surface_attributes(cls, obj): pass
+    def get_active_style_type(cls): pass
     def get_context(cls, obj): pass
     def get_name(cls, obj): pass
     def get_style(cls, obj): pass
@@ -409,7 +446,9 @@ class Style:
     def get_surface_shading_style(cls, obj): pass
     def get_surface_texture_style(cls, obj): pass
     def get_uv_maps(cls, representation): pass
+    def import_presentation_styles(cls, style_type): pass
     def import_surface_attributes(cls, style, obj): pass
+    def is_editing_styles(cls): pass
 
 
 @interface
diff --git a/src/blenderbim/blenderbim/core/unit.py b/src/blenderbim/blenderbim/core/unit.py
index 4c38e370ca..f5fd274a66 100644
--- a/src/blenderbim/blenderbim/core/unit.py
+++ b/src/blenderbim/blenderbim/core/unit.py
@@ -32,7 +32,9 @@ def assign_scene_units(ifc, unit):
         areaunit = ifc.run("unit.add_conversion_based_unit", name=area_name)
         volumeunit = ifc.run("unit.add_conversion_based_unit", name=volume_name)
 
-    ifc.run("unit.assign_unit", units=[lengthunit, areaunit, volumeunit])
+    planeangleunit = ifc.run("unit.add_conversion_based_unit", name="degree")
+
+    ifc.run("unit.assign_unit", units=[lengthunit, areaunit, volumeunit, planeangleunit])
 
 
 def assign_unit(ifc, unit_tool, unit=None):
@@ -77,6 +79,12 @@ def add_context_dependent_unit(ifc, unit, unit_type=None, name=None):
     return result
 
 
+def add_conversion_based_unit(ifc, unit, name=None):
+    result = ifc.run("unit.add_conversion_based_unit", name=name)
+    unit.import_units()
+    return result
+
+
 def enable_editing_unit(unit_tool, unit=None):
     unit_tool.set_active_unit(unit)
     unit_tool.import_unit_attributes(unit)
diff --git a/src/blenderbim/blenderbim/tool/document.py b/src/blenderbim/blenderbim/tool/document.py
index a8b80b975d..ce1e68ce49 100644
--- a/src/blenderbim/blenderbim/tool/document.py
+++ b/src/blenderbim/blenderbim/tool/document.py
@@ -25,8 +25,20 @@ from blenderbim.bim import import_ifc
 
 class Document(blenderbim.core.tool.Document):
     @classmethod
-    def disable_document_assignment_ui(cls, obj):
-        obj.BIMObjectDocumentProperties.is_adding = ""
+    def add_breadcrumb(cls, document):
+        props = bpy.context.scene.BIMDocumentProperties
+        new = props.breadcrumbs.add()
+        new.name = str(document.id())
+
+    @classmethod
+    def clear_breadcrumbs(cls):
+        props = bpy.context.scene.BIMDocumentProperties
+        props.breadcrumbs.clear()
+
+    @classmethod
+    def clear_document_tree(cls):
+        props = bpy.context.scene.BIMDocumentProperties
+        props.documents.clear()
 
     @classmethod
     def disable_editing_document(cls):
@@ -34,24 +46,22 @@ class Document(blenderbim.core.tool.Document):
 
     @classmethod
     def disable_editing_ui(cls):
-        bpy.context.scene.BIMDocumentProperties.is_editing = ""
+        bpy.context.scene.BIMDocumentProperties.is_editing = False
 
     @classmethod
-    def enable_document_assignment_ui(cls, obj):
-        obj.BIMObjectDocumentProperties.is_adding = "IfcDocumentReference"
-
-    @classmethod
-    def enable_information_editing_ui(cls):
-        bpy.context.scene.BIMDocumentProperties.is_editing = "information"
-
-    @classmethod
-    def enable_reference_editing_ui(cls):
-        bpy.context.scene.BIMDocumentProperties.is_editing = "reference"
+    def enable_editing_ui(cls):
+        bpy.context.scene.BIMDocumentProperties.is_editing = True
 
     @classmethod
     def export_document_attributes(cls):
         return blenderbim.bim.helper.export_attributes(bpy.context.scene.BIMDocumentProperties.document_attributes)
 
+    @classmethod
+    def get_active_breadcrumb(cls):
+        props = bpy.context.scene.BIMDocumentProperties
+        if len(props.breadcrumbs):
+            return tool.Ifc.get().by_id(int(props.breadcrumbs[-1].name))
+
     @classmethod
     def import_document_attributes(cls, document):
         props = bpy.context.scene.BIMDocumentProperties
@@ -59,35 +69,64 @@ class Document(blenderbim.core.tool.Document):
         blenderbim.bim.helper.import_attributes2(document, props.document_attributes)
 
     @classmethod
-    def import_information(cls):
+    def import_project_documents(cls):
         props = bpy.context.scene.BIMDocumentProperties
         props.documents.clear()
-        for element in tool.Ifc.get().by_type("IfcDocumentInformation"):
-            new = props.documents.add()
-            new.ifc_definition_id = element.id()
-            new.name = element.Name or "Unnamed"
-            if tool.Ifc.get_schema() == "IFC2X3":
-                new.identification = element.DocumentId or "*"
-            else:
-                new.identification = element.Identification or "*"
+        project = tool.Ifc.get().by_type("IfcProject")[0]
+        for rel in project.HasAssociations or []:
+            if rel.is_a("IfcRelAssociatesDocument") and rel.RelatingDocument.is_a("IfcDocumentInformation"):
+                element = rel.RelatingDocument
+                new = props.documents.add()
+                new.ifc_definition_id = element.id()
+                new.name = element.Name or "Unnamed"
+                new.is_information = True
+                if tool.Ifc.get_schema() == "IFC2X3":
+                    new.identification = element.DocumentId or "*"
+                else:
+                    new.identification = element.Identification or "*"
 
     @classmethod
-    def import_references(cls):
+    def import_references(cls, document):
         props = bpy.context.scene.BIMDocumentProperties
-        props.documents.clear()
-        for element in tool.Ifc.get().by_type("IfcDocumentReference"):
-            new = props.documents.add()
-            new.ifc_definition_id = element.id()
-            new.name = element.Name or "Unnamed"
-            if tool.Ifc.get_schema() == "IFC2X3":
+        if tool.Ifc.get_schema() == "IFC2X3":
+            for element in document.DocumentReferences or []:
+                new = props.documents.add()
+                new.ifc_definition_id = element.id()
+                new.name = element.Name or "Unnamed"
                 new.identification = element.ItemReference or "*"
-            else:
+                new.is_information = False
+        else:
+            for element in document.HasDocumentReferences:
+                new = props.documents.add()
+                new.ifc_definition_id = element.id()
+                new.name = element.Name or "Unnamed"
                 new.identification = element.Identification or "*"
+                new.is_information = False
+
+    @classmethod
+    def import_subdocuments(cls, document):
+        props = bpy.context.scene.BIMDocumentProperties
+        if document.IsPointer:
+            for element in document.IsPointer[0].RelatedDocuments or []:
+                new = props.documents.add()
+                new.ifc_definition_id = element.id()
+                new.name = element.Name or "Unnamed"
+                new.is_information = True
+                if tool.Ifc.get_schema() == "IFC2X3":
+                    new.identification = element.DocumentId or "*"
+                else:
+                    new.identification = element.Identification or "*"
 
     @classmethod
     def is_document_information(cls, document):
         return document.is_a("IfcDocumentInformation")
 
+    @classmethod
+    def remove_latest_breadcrumb(cls):
+        props = bpy.context.scene.BIMDocumentProperties
+        if len(props.breadcrumbs):
+            props.breadcrumbs.remove(len(props.breadcrumbs) - 1)
+
     @classmethod
     def set_active_document(cls, document):
         bpy.context.scene.BIMDocumentProperties.active_document_id = document.id()
diff --git a/src/blenderbim/blenderbim/tool/drawing.py b/src/blenderbim/blenderbim/tool/drawing.py
index 8971e3b2d5..5dd7d8022a 100644
--- a/src/blenderbim/blenderbim/tool/drawing.py
+++ b/src/blenderbim/blenderbim/tool/drawing.py
@@ -19,13 +19,18 @@
 import os
 import re
 import bpy
+import math
+import bmesh
 import mathutils
 import webbrowser
+import numpy as np
 import blenderbim.core.tool
+import blenderbim.core.geometry
 import blenderbim.tool as tool
 import ifcopenshell.util.representation
 import blenderbim.bim.module.drawing.sheeter as sheeter
 import blenderbim.bim.module.drawing.annotation as annotation
+import blenderbim.bim.module.drawing.helper as helper
 
 
 class Drawing(blenderbim.core.tool.Drawing):
@@ -83,6 +88,10 @@ class Drawing(blenderbim.core.tool.Drawing):
             if obj:
                 bpy.data.objects.remove(obj)
 
+    @classmethod
+    def delete_object(cls, obj):
+        bpy.data.objects.remove(obj)
+
     @classmethod
     def disable_editing_drawings(cls):
         bpy.context.scene.DocProperties.is_editing_drawings = False
@@ -260,19 +269,49 @@ class Drawing(blenderbim.core.tool.Drawing):
             new = bpy.context.scene.DocProperties.drawings.add()
             new.ifc_definition_id = drawing.id()
             new.name = drawing.Name or "Unnamed"
+            new.target_view = cls.get_drawing_target_view(drawing)
 
     @classmethod
     def import_sheets(cls):
-        bpy.context.scene.DocProperties.sheets.clear()
+        props = bpy.context.scene.DocProperties
+        expanded_sheets = {s.ifc_definition_id for s in props.sheets if s.is_expanded}
+        props.sheets.clear()
         sheets = [d for d in tool.Ifc.get().by_type("IfcDocumentInformation") if d.Scope == "DOCUMENTATION"]
         for sheet in sheets:
-            new = bpy.context.scene.DocProperties.sheets.add()
+            new = props.sheets.add()
             new.ifc_definition_id = sheet.id()
             if tool.Ifc.get_schema() == "IFC2X3":
                 new.identification = sheet.DocumentId
             else:
                 new.identification = sheet.Identification
             new.name = sheet.Name
+            new.is_sheet = True
+            new.is_expanded = sheet.id() in expanded_sheets
+
+            if not new.is_expanded:
+                continue
+
+            if tool.Ifc.get_schema() == "IFC2X3":
+                references = sheet.DocumentReferences or []
+            else:
+                references = sheet.HasDocumentReferences or []
+
+            for reference in references:
+                new = props.sheets.add()
+                new.ifc_definition_id = reference.id()
+                new.is_sheet = False
+
+                if tool.Ifc.get_schema() == "IFC2X3":
+                    new.identification = reference.ItemReference or "X"
+                    element = [
+                        r for r in tool.Ifc.by_type("IfcRelAssociatesDocument") if r.RelatingDocument == reference
+                    ][0].RelatedObjects[0]
+                else:
+                    new.identification = reference.Identification or "X"
+                    element = reference.DocumentRefForObjects[0].RelatedObjects[0]
+
+                new.name = element.Name
+                new.reference_type = "DRAWING"
 
     @classmethod
     def import_text_attributes(cls, obj):
@@ -349,3 +388,335 @@ class Drawing(blenderbim.core.tool.Drawing):
             for variable in re.findall("{{.*?}}", value):
                 value = value.replace(variable, selector.get_element_value(product, variable[2:-2]) or "")
         obj.BIMTextProperties.value = value
+
+    # TODO below this point is highly experimental prototype code with no tests
+
+    @classmethod
+    def generate_drawing_name(cls, target_view, location_hint):
+        if target_view in ("PLAN_VIEW", "REFLECTED_PLAN_VIEW") and location_hint:
+            location = tool.Ifc.get().by_id(location_hint)
+            if target_view == "REFLECTED_PLAN_VIEW":
+                target_view = "RCP_VIEW"
+            return (location.Name or "UNNAMED").upper() + " " + target_view.split("_")[0]
+        elif target_view in ("SECTION_VIEW", "ELEVATION_VIEW") and location_hint:
+            return location_hint + " " + target_view.split("_")[0]
+        return target_view
+
+    @classmethod
+    def get_potential_reference_elements(cls, drawing):
+        elements = []
+        existing_references = cls.get_group_elements(cls.get_drawing_group(drawing))
+        for element in tool.Ifc.get().by_type("IfcAnnotation"):
+            if element in existing_references or element == drawing:
+                continue
+            if element.ObjectType == "DRAWING":
+                psets = ifcopenshell.util.element.get_psets(element)
+                if psets.get("EPset_Drawing", {}).get("TargetView", None) in ("SECTION_VIEW", "ELEVATION_VIEW"):
+                    elements.append(element)
+        for element in tool.Ifc.get().by_type("IfcGridAxis"):
+            elements.append(element)
+        return elements
+
+    @classmethod
+    def get_drawing_reference_annotation(cls, drawing, reference_element):
+        if drawing == reference_element:
+            return True
+        for element in cls.get_group_elements(cls.get_drawing_group(drawing)):
+            if element.is_a("IfcAnnotation"):
+                for rel in element.HasAssignments:
+                    if rel.is_a("IfcRelAssignsToProduct"):
+                        if rel.RelatingProduct == reference_element:
+                            return element
+                        # We cannot associate IfcGridAxis directly, so we establish a convention:
+                        # IfcRelAssignsToProduct.RelatingProduct = IfcGrid
+                        # IfcRelAssignsToProduct.Name = IfcGridAxis.AxisTag
+                        elif reference_element.is_a("IfcGridAxis") and rel.Name == reference_element.AxisTag:
+                            return element
+
+    @classmethod
+    def generate_reference_annotation(cls, drawing, reference_element, context):
+        if reference_element.is_a("IfcGridAxis"):
+            return cls.generate_grid_axis_reference_annotation(drawing, reference_element, context)
+        elif reference_element.is_a("IfcAnnotation") and reference_element.ObjectType == "DRAWING":
+            psets = ifcopenshell.util.element.get_psets(reference_element)
+            target_view = psets.get("EPset_Drawing", {}).get("TargetView", None)
+            if target_view == "ELEVATION_VIEW":
+                return cls.generate_elevation_reference_annotation(drawing, reference_element, context)
+            elif target_view == "SECTION_VIEW":
+                return cls.generate_section_reference_annotation(drawing, reference_element, context)
+
+    @classmethod
+    def generate_section_reference_annotation(cls, drawing, reference_element, context):
+        reference_obj = tool.Ifc.get_object(reference_element)
+        reference_obj.matrix_world
+        camera = tool.Ifc.get_object(drawing)
+        bounds = helper.ortho_view_frame(camera.data) if camera.data.type == "ORTHO" else None
+
+        def to_camera_coords(camera, reference_obj):
+            mat = reference_obj.matrix_world.copy()
+            xyz = camera.matrix_world.inverted() @ reference_obj.matrix_world.translation
+            xyz[2] = 0
+            xyz = camera.matrix_world @ xyz
+            mat[0][3] = xyz[0]
+            mat[1][3] = xyz[1]
+            mat[2][3] = xyz[2]
+            annotation_offset = mathutils.Vector((0, 0, -camera.data.clip_start - 0.05))
+            annotation_offset = camera.matrix_world.to_quaternion() @ annotation_offset
+            mat[0][3] += annotation_offset[0]
+            mat[1][3] += annotation_offset[1]
+            mat[2][3] += annotation_offset[2]
+            return mat
+
+        def clip_to_camera_boundary(mesh, bounds):
+            mesh.verts.ensure_lookup_table()
+            points = [v.co for v in mesh.verts[0:2]]
+            points = helper.clip_segment(bounds, points)
+            if points is None:
+                return None
+            mesh.verts[0].co = points[0]
+            mesh.verts[1].co = points[1]
+            return mesh
+
+        if cls.is_perpendicular(camera, reference_obj) and cls.is_intersecting(camera, reference_obj):
+            reference_mesh = cls.get_camera_block(reference_obj)
+            obj_matrix = to_camera_coords(camera, reference_obj)
+
+            # The reference mesh vertices represent a view cube. To convert this into a section line we:
+            # 1. Select the 4 +Z vertices local to the reference element. This is the cutting plane.
+            verts_local_to_reference = [reference_obj.matrix_world.inverted() @ v for v in reference_mesh["verts"]]
+            cutting_plane_verts = sorted(verts_local_to_reference, key=lambda x: x.z)[-4:]
+            global_cutting_plane_verts = [reference_obj.matrix_world @ v for v in cutting_plane_verts]
+            # 2. Project the cutting plane onto our viewing camera.
+            verts_local_to_camera = [camera.matrix_world.inverted() @ v for v in global_cutting_plane_verts]
+            # 3. Collapse verts with the same XY coords, and set Z to be just below the clip_start so it's visible
+            collapsed_verts = []
+            for vert in verts_local_to_camera:
+                if not [True for v in collapsed_verts if (vert.xy - v.xy).length < 1e-2]:
+                    collapsed_verts.append(mathutils.Vector((vert.x, vert.y, -camera.data.clip_start - 0.05)))
+            # 4. The first two vertices is the section line
+            section_line = collapsed_verts[0:2]
+            global_section_line = [camera.matrix_world @ v for v in section_line]
+            local_section_line = [obj_matrix.inverted() @ v for v in global_section_line]
+
+            mesh = bpy.data.meshes.new(name="Annotation")
+            mesh.from_pydata(local_section_line, [(0, 1)], [])
+            bm = bmesh.new()
+            bm.from_mesh(mesh)
+            bm = clip_to_camera_boundary(bm, bounds)
+            bm.to_mesh(mesh)
+            bm.free()
+
+            obj = bpy.data.objects.new(reference_obj.name, mesh)
+            obj.matrix_world = obj_matrix
+
+            element = cls.run_root_assign_class(
+                obj=obj,
+                ifc_class="IfcAnnotation",
+                predefined_type="SECTION",
+                should_add_representation=True,
+                context=context,
+                ifc_representation_class=None,
+            )
+            return element
+
+    @classmethod
+    def generate_elevation_reference_annotation(cls, drawing, reference_element, context):
+        reference_obj = tool.Ifc.get_object(reference_element)
+        reference_obj.matrix_world
+        camera = tool.Ifc.get_object(drawing)
+
+        def to_camera_coords(camera, reference_obj):
+            mat = reference_obj.matrix_world.copy()
+            xyz = camera.matrix_world.inverted() @ reference_obj.matrix_world.translation
+            xyz[2] = 0
+            xyz = camera.matrix_world @ xyz
+            mat[0][3] = xyz[0]
+            mat[1][3] = xyz[1]
+            mat[2][3] = xyz[2]
+            annotation_offset = mathutils.Vector((0, 0, -camera.data.clip_start - 0.05))
+            annotation_offset = camera.matrix_world.to_quaternion() @ annotation_offset
+            mat[0][3] += annotation_offset[0]
+            mat[1][3] += annotation_offset[1]
+            mat[2][3] += annotation_offset[2]
+            return mat
+
+        if cls.is_perpendicular(camera, reference_obj) and cls.is_intersecting(camera, reference_obj):
+            obj = bpy.data.objects.new(reference_obj.name, None)
+            obj.empty_display_size = 0.1
+            obj.matrix_world = to_camera_coords(camera, reference_obj)
+
+            element = cls.run_root_assign_class(
+                obj=obj,
+                ifc_class="IfcAnnotation",
+                predefined_type="ELEVATION",
+                should_add_representation=False,
+                context=context,
+                ifc_representation_class=None,
+            )
+            return element
+
+    @classmethod
+    def generate_grid_axis_reference_annotation(cls, drawing, reference_element, context):
+        target_view = tool.Drawing.get_drawing_target_view(drawing)
+
+        camera = tool.Ifc.get_object(drawing)
+
+        is_ortho = camera.data.type == "ORTHO"
+        bounds = helper.ortho_view_frame(camera.data) if is_ortho else None
+        clipping = is_ortho and target_view in ("PLAN_VIEW", "REFLECTED_PLAN_VIEW")
+        elevating = is_ortho and target_view in ("ELEVATION_VIEW", "SECTION_VIEW")
+
+        def clone(src):
+            dst = src.copy()
+            dst.data = dst.data.copy()
+            dst.name = dst.name.replace("IfcGridAxis/", "")
+            dst.BIMObjectProperties.ifc_definition_id = 0
+            dst.data.BIMMeshProperties.ifc_definition_id = 0
+            return dst
+
+        def disassemble(obj):
+            mesh = bmesh.new()
+            mesh.verts.ensure_lookup_table()
+            mesh.from_mesh(obj.data)
+            return obj, mesh
+
+        def assemble(obj, mesh):
+            mesh.to_mesh(obj.data)
+            return obj
+
+        def to_camera_coords(obj, mesh):
+            mesh.transform(camera.matrix_world.inverted() @ obj.matrix_world)
+            obj.matrix_world = camera.matrix_world
+            annotation_offset = mathutils.Vector((0, 0, -camera.data.clip_start - 0.05))
+            annotation_offset = camera.matrix_world.to_quaternion() @ annotation_offset
+            obj.matrix_world[0][3] += annotation_offset[0]
+            obj.matrix_world[1][3] += annotation_offset[1]
+            obj.matrix_world[2][3] += annotation_offset[2]
+            return obj, mesh
+
+        def clip_to_camera_boundary(mesh):
+            mesh.verts.ensure_lookup_table()
+            points = [v.co for v in mesh.verts[0:2]]
+            points = helper.clip_segment(bounds, points)
+            if points is None:
+                return None
+            mesh.verts[0].co = points[0]
+            mesh.verts[1].co = points[1]
+            return mesh
+
+        def draw_grids_vertically(mesh):
+            mesh.verts.ensure_lookup_table()
+            points = [v.co for v in mesh.verts[0:2]]
+            points = helper.elevate_segment(bounds, points)
+            if points is None:
+                return None
+            points = helper.clip_segment(bounds, points)
+            if points is None:
+                return None
+            mesh.verts[0].co = points[0]
+            mesh.verts[1].co = points[1]
+            return mesh
+
+        obj = tool.Ifc.get_object(reference_element)
+        if not obj:
+            return
+        obj, mesh = to_camera_coords(*disassemble(clone(obj)))
+
+        if clipping:
+            mesh = clip_to_camera_boundary(mesh)
+        elif elevating:
+            mesh = draw_grids_vertically(mesh)
+
+        if mesh is None:
+            return
+
+        assemble(obj, mesh)
+
+        element = cls.run_root_assign_class(
+            obj=obj,
+            ifc_class="IfcAnnotation",
+            predefined_type="GRID",
+            should_add_representation=True,
+            context=context,
+            ifc_representation_class=None,
+        )
+        return element
+
+    @classmethod
+    def is_perpendicular(cls, a, b):
+        axes = [mathutils.Vector((1, 0, 0)), mathutils.Vector((0, 1, 0)), mathutils.Vector((0, 0, 1))]
+        a_quaternion = a.matrix_world.to_quaternion()
+        b_quaternion = b.matrix_world.to_quaternion()
+        for axis in axes:
+            if abs((a_quaternion @ axis).angle((b_quaternion @ axis)) - (math.pi / 2)) < 1e-5:
+                return True
+        return False
+
+    @classmethod
+    def get_camera_block(cls, obj):
+        raster_x = obj.data.BIMCameraProperties.raster_x
+        raster_y = obj.data.BIMCameraProperties.raster_y
+
+        if raster_x > raster_y:
+            width = obj.data.ortho_scale
+            height = width / raster_x * raster_y
+        else:
+            height = obj.data.ortho_scale
+            width = height / raster_y * raster_x
+        depth = obj.data.clip_end
+
+        verts = (
+            obj.matrix_world @ mathutils.Vector((-width / 2, -height / 2, -depth)),
+            obj.matrix_world @ mathutils.Vector((-width / 2, -height / 2, 0)),
+            obj.matrix_world @ mathutils.Vector((-width / 2, height / 2, -depth)),
+            obj.matrix_world @ mathutils.Vector((-width / 2, height / 2, 0)),
+            obj.matrix_world @ mathutils.Vector((width / 2, -height / 2, -depth)),
+            obj.matrix_world @ mathutils.Vector((width / 2, -height / 2, 0)),
+            obj.matrix_world @ mathutils.Vector((width / 2, height / 2, -depth)),
+            obj.matrix_world @ mathutils.Vector((width / 2, height / 2, 0)),
+        )
+        faces = [
+            [0, 1, 3, 2],
+            [2, 3, 7, 6],
+            [6, 7, 5, 4],
+            [4, 5, 1, 0],
+            [2, 6, 4, 0],
+            [7, 3, 1, 5],
+        ]
+        return {"verts": verts, "faces": faces}
+
+    @classmethod
+    def is_intersecting(cls, a, b):
+        a_block = cls.get_camera_block(a)
+        a_tree = mathutils.bvhtree.BVHTree.FromPolygons(a_block["verts"], a_block["faces"])
+        b_block = cls.get_camera_block(b)
+        b_tree = mathutils.bvhtree.BVHTree.FromPolygons(b_block["verts"], b_block["faces"])
+        return bool(a_tree.overlap(b_tree))
+
+    @classmethod
+    def sync_object_representation(cls, obj):
+        bpy.ops.bim.update_representation(obj=obj.name)
+
+    @classmethod
+    def sync_object_placement(cls, obj):
+        blender_matrix = np.array(obj.matrix_world)
+        element = tool.Ifc.get_entity(obj)
+        if (obj.scale - mathutils.Vector((1.0, 1.0, 1.0))).length > 1e-4:
+            bpy.ops.bim.update_representation(obj=obj.name)
+            return element
+        if element.is_a("IfcGridAxis"):
+            return cls.sync_grid_axis_object_placement(obj, element)
+        if not hasattr(element, "ObjectPlacement"):
+            return
+        blenderbim.core.geometry.edit_object_placement(tool.Ifc, tool.Geometry, tool.Surveyor, obj=obj)
+        return element
+
+    @classmethod
+    def sync_grid_axis_object_placement(cls, obj, element):
+        grid = (element.PartOfU or element.PartOfV or element.PartOfW)[0]
+        grid_obj = tool.Ifc.get_object(grid)
+        if grid_obj:
+            cls.sync_object_placement(grid_obj)
+            if grid_obj.matrix_world != obj.matrix_world:
+                bpy.ops.bim.update_representation(obj=obj.name)
+        tool.Geometry.record_object_position(obj)
diff --git a/src/blenderbim/blenderbim/tool/ifc.py b/src/blenderbim/blenderbim/tool/ifc.py
index ad719f9c55..d487aafbcb 100644
--- a/src/blenderbim/blenderbim/tool/ifc.py
+++ b/src/blenderbim/blenderbim/tool/ifc.py
@@ -17,6 +17,7 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import bpy
+import numpy as np
 import ifcopenshell.api
 import blenderbim.core.tool
 from blenderbim.bim.ifc import IfcStore
@@ -44,6 +45,26 @@ class Ifc(blenderbim.core.tool.Ifc):
         if IfcStore.get_file():
             return IfcStore.get_file().schema
 
+    @classmethod
+    def is_deleted(cls, element):
+        return element.id() in IfcStore.deleted_ids
+
+    @classmethod
+    def is_edited(cls, obj):
+        return list(obj.scale) != [1.0, 1.0, 1.0] or obj in IfcStore.edited_objs
+
+    @classmethod
+    def is_moved(cls, obj):
+        if not obj.BIMObjectProperties.location_checksum:
+            return True  # Let's be conservative
+        loc_check = np.frombuffer(eval(obj.BIMObjectProperties.location_checksum))
+        rot_check = np.frombuffer(eval(obj.BIMObjectProperties.rotation_checksum))
+        loc_real = np.array(obj.matrix_world.translation).flatten()
+        rot_real = np.array(obj.matrix_world.to_3x3()).flatten()
+        if np.allclose(loc_check, loc_real, atol=1e-4) and np.allclose(rot_check, rot_real, atol=1e-2):
+            return False
+        return True
+
     @classmethod
     def schema(cls):
         return IfcStore.get_schema()
diff --git a/src/blenderbim/blenderbim/tool/material.py b/src/blenderbim/blenderbim/tool/material.py
index 1acb411b62..9ac4345587 100644
--- a/src/blenderbim/blenderbim/tool/material.py
+++ b/src/blenderbim/blenderbim/tool/material.py
@@ -27,3 +27,53 @@ class Material(blenderbim.core.tool.Material):
     @classmethod
     def add_default_material_object(cls):
         return bpy.data.materials.new("Default")
+
+    @classmethod
+    def delete_object(cls, obj):
+        bpy.data.materials.remove(obj)
+
+    @classmethod
+    def disable_editing_materials(cls):
+        bpy.context.scene.BIMMaterialProperties.is_editing = False
+
+    @classmethod
+    def enable_editing_materials(cls):
+        bpy.context.scene.BIMMaterialProperties.is_editing = True
+
+    @classmethod
+    def get_active_material_type(cls):
+        return bpy.context.scene.BIMMaterialProperties.material_type
+
+    @classmethod
+    def get_elements_by_material(cls, material):
+        return set(ifcopenshell.util.element.get_elements_by_material(tool.Ifc.get(), material))
+
+    @classmethod
+    def get_name(cls, obj):
+        return obj.name
+
+    @classmethod
+    def import_material_definitions(cls, material_type):
+        props = bpy.context.scene.BIMMaterialProperties
+        props.materials.clear()
+        for material in tool.Ifc.get().by_type(material_type):
+            new = props.materials.add()
+            new.ifc_definition_id = material.id()
+            if material.is_a("IfcMaterialLayerSet"):
+                new.name = material.LayerSetName or "Unnamed"
+            elif material.is_a("IfcMaterialList"):
+                new.name = "Unnamed"
+            else:
+                new.name = material.Name or "Unnamed"
+            new.total_elements = len(set(ifcopenshell.util.element.get_elements_by_material(tool.Ifc.get(), material)))
+
+    @classmethod
+    def is_editing_materials(cls):
+        return bpy.context.scene.BIMMaterialProperties.is_editing
+
+    @classmethod
+    def select_elements(cls, elements):
+        for element in elements:
+            obj = tool.Ifc.get_object(element)
+            if obj:
+                obj.select_set(True)
diff --git a/src/blenderbim/blenderbim/tool/style.py b/src/blenderbim/blenderbim/tool/style.py
index 80f7248d5d..caa87ff36c 100644
--- a/src/blenderbim/blenderbim/tool/style.py
+++ b/src/blenderbim/blenderbim/tool/style.py
@@ -16,6 +16,7 @@
 # You should have received a copy of the GNU General Public License
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
+import bpy
 import ifcopenshell
 import blenderbim.core.tool
 import blenderbim.tool as tool
@@ -31,14 +32,26 @@ class Style(blenderbim.core.tool.Style):
     def disable_editing(cls, obj):
         obj.BIMStyleProperties.is_editing = False
 
+    @classmethod
+    def disable_editing_styles(cls):
+        bpy.context.scene.BIMStylesProperties.is_editing = False
+
     @classmethod
     def enable_editing(cls, obj):
         obj.BIMStyleProperties.is_editing = True
 
+    @classmethod
+    def enable_editing_styles(cls):
+        bpy.context.scene.BIMStylesProperties.is_editing = True
+
     @classmethod
     def export_surface_attributes(cls, obj):
         return blenderbim.bim.helper.export_attributes(obj.BIMStyleProperties.attributes)
 
+    @classmethod
+    def get_active_style_type(cls):
+        return bpy.context.scene.BIMStylesProperties.style_type
+
     @classmethod
     def get_context(cls, obj):
         return ifcopenshell.util.representation.get_context(tool.Ifc.get(), "Model", "Body", "MODEL_VIEW")
@@ -166,7 +179,20 @@ class Style(blenderbim.core.tool.Style):
                 results.append(uv_map)
         return results
 
+    @classmethod
+    def import_presentation_styles(cls, style_type):
+        props = bpy.context.scene.BIMStylesProperties
+        props.styles.clear()
+        for style in tool.Ifc.get().by_type(style_type):
+            new = props.styles.add()
+            new.ifc_definition_id = style.id()
+            new.name = style.Name or "Unnamed"
+
     @classmethod
     def import_surface_attributes(cls, style, obj):
         obj.BIMStyleProperties.attributes.clear()
         blenderbim.bim.helper.import_attributes2(style, obj.BIMStyleProperties.attributes)
+
+    @classmethod
+    def is_editing_styles(cls):
+        return bpy.context.scene.BIMStylesProperties.is_editing
diff --git a/src/blenderbim/docs/blenderbim/developer_guide.rst b/src/blenderbim/docs/blenderbim/developer_guide.rst
index fa337a5024..89e20e53fd 100644
--- a/src/blenderbim/docs/blenderbim/developer_guide.rst
+++ b/src/blenderbim/docs/blenderbim/developer_guide.rst
@@ -63,7 +63,7 @@ architecture flow charts and diagrams. The code and its comments will guide you
 through the process.
 
 Before playing with the demo module, you may want to switch to using a source
-installation. See :ref:`blenderbim/installation` for details.
+installation. See `blenderbim/installation <./installation.rst>`_ for details.
 
 To see the demo module in action, you'll need to enable it. In
 ``src/blenderbim/blenderbim/bim/__init__.py``, uncomment the line for the demo
@@ -95,8 +95,8 @@ and how to test and structure it so that you can build incredibly complex
 features in a maintainable way.
 
 Tests for quality checking also exist. The system is designed so that you can
-do "Test Driven Development". For reference on how to run these tests, see
-:ref:`blenderbim/running_tests` for details. You can find the tests here:
+do "Test Driven Development". For reference on how to run these tests, see `blenderbim/running_tests <./running_tests.rst>`_
+for details. You can find the tests here:
 
 ::
 
diff --git a/src/blenderbim/pytest.ini b/src/blenderbim/pytest.ini
index 2da67b7e82..5cd46aa294 100644
--- a/src/blenderbim/pytest.ini
+++ b/src/blenderbim/pytest.ini
@@ -7,6 +7,7 @@ markers =
     context
     debug
     demo
+    document
     drawing
     geometry
     library
diff --git a/src/blenderbim/test/bim/feature/aggregate.feature b/src/blenderbim/test/bim/feature/aggregate.feature
index 3d0d15d1ba..acb7197252 100644
--- a/src/blenderbim/test/bim/feature/aggregate.feature
+++ b/src/blenderbim/test/bim/feature/aggregate.feature
@@ -49,7 +49,7 @@ Scenario: Add aggregate
     When I press "bim.add_aggregate"
     Then the object "IfcWall/Cube" is in the collection "IfcElementAssembly/Assembly"
     And the object "IfcElementAssembly/Assembly" is in the collection "IfcElementAssembly/Assembly"
-    And the collection "IfcElementAssembly/Assembly" is in the collection "IfcProject/My Project"
+    And the collection "IfcElementAssembly/Assembly" is in the collection "IfcBuildingStorey/My Storey"
 
 Scenario: Add aggregate - with the aggregate inheriting the existing spatial collection
     Given an empty IFC project
diff --git a/src/blenderbim/test/bim/feature/document.feature b/src/blenderbim/test/bim/feature/document.feature
new file mode 100644
index 0000000000..db14740fbe
--- /dev/null
+++ b/src/blenderbim/test/bim/feature/document.feature
@@ -0,0 +1,112 @@
+@document
+Feature: Document
+
+Scenario: Load project documents
+    Given an empty IFC project
+    When I press "bim.load_project_documents"
+    Then nothing happens
+
+Scenario: Load document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    When I press "bim.load_document(document={information})"
+    Then nothing happens
+
+Scenario: Load parent document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    And I press "bim.load_document(document={information})"
+    When I press "bim.load_parent_document"
+    Then nothing happens
+
+Scenario: Disable document editing UI
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    When I press "bim.disable_document_editing_ui"
+    Then nothing happens
+
+Scenario: Enable editing document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    When I press "bim.enable_editing_document(document={information})"
+    Then nothing happens
+
+Scenario: Disable editing document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    And I press "bim.enable_editing_document(document={information})"
+    When I press "bim.disable_editing_document"
+    Then nothing happens
+
+Scenario: Add information
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    When I press "bim.add_information"
+    Then nothing happens
+
+Scenario: Add document reference
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    And I press "bim.load_document(document={information})"
+    When I press "bim.add_document_reference"
+    Then nothing happens
+
+Scenario: Edit document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    And I press "bim.enable_editing_document(document={information})"
+    When I press "bim.edit_document"
+    Then nothing happens
+
+Scenario: Remove document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    When I press "bim.remove_document(document={information})"
+    Then nothing happens
+
+Scenario: Assign document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    And I press "bim.load_document(document={information})"
+    And I press "bim.add_document_reference"
+    And the variable "reference" is "{ifc}.by_type('IfcDocumentReference')[-1].id()"
+    And I add a cube
+    And the object "Cube" is selected
+    And I set "scene.BIMRootProperties.ifc_product" to "IfcElement"
+    And I set "scene.BIMRootProperties.ifc_class" to "IfcWall"
+    And I press "bim.assign_class"
+    When I press "bim.assign_document(document={reference})"
+    Then nothing happens
+
+Scenario: Unassign document
+    Given an empty IFC project
+    And I press "bim.load_project_documents"
+    And I press "bim.add_information"
+    And the variable "information" is "{ifc}.by_type('IfcDocumentInformation')[-1].id()"
+    And I press "bim.load_document(document={information})"
+    And I press "bim.add_document_reference"
+    And the variable "reference" is "{ifc}.by_type('IfcDocumentReference')[-1].id()"
+    And I add a cube
+    And the object "Cube" is selected
+    And I set "scene.BIMRootProperties.ifc_product" to "IfcElement"
+    And I set "scene.BIMRootProperties.ifc_class" to "IfcWall"
+    And I press "bim.assign_class"
+    And I press "bim.assign_document(document={reference})"
+    When I press "bim.unassign_document(document={reference})"
+    Then nothing happens
diff --git a/src/blenderbim/test/bim/feature/geometry.feature b/src/blenderbim/test/bim/feature/geometry.feature
index 5bf3491be0..dae44cff62 100644
--- a/src/blenderbim/test/bim/feature/geometry.feature
+++ b/src/blenderbim/test/bim/feature/geometry.feature
@@ -19,7 +19,7 @@ Scenario: Add representation
     And I press "bim.assign_class"
     And the object "IfcWall/Cube" is selected
     Then the object "IfcWall/Cube" data is a "Tessellation" representation of "Model/Body/MODEL_VIEW"
-    When the variable "context" is "{ifc}.by_type('IfcGeometricRepresentationSubContext')[-1].id()"
+    When the variable "context" is "[c for c in {ifc}.by_type('IfcGeometricRepresentationSubContext') if c.TargetView == 'PLAN_VIEW'][0].id()"
     And I set "scene.BIMRootProperties.contexts" to "{context}"
     And I press "bim.add_representation"
     Then the object "IfcWall/Cube" data is a "Annotation2D" representation of "Plan/Annotation/PLAN_VIEW"
@@ -36,7 +36,7 @@ Scenario: Add representation - add a new representation to a typed instance
     Then the object "IfcWall/Wall" data is a "Tessellation" representation of "Model/Body/MODEL_VIEW"
     And the object "IfcWall/Wall.001" data is a "Tessellation" representation of "Model/Body/MODEL_VIEW"
     When the object "IfcWall/Wall" is selected
-    And the variable "context" is "{ifc}.by_type('IfcGeometricRepresentationSubContext')[-1].id()"
+    And the variable "context" is "[c for c in {ifc}.by_type('IfcGeometricRepresentationSubContext') if c.TargetView == 'PLAN_VIEW'][0].id()"
     And I set "scene.BIMRootProperties.contexts" to "{context}"
     And I press "bim.add_representation"
     Then the object "IfcWall/Wall" data is a "Annotation2D" representation of "Plan/Annotation/PLAN_VIEW"
@@ -195,7 +195,7 @@ Scenario: Update representation - updating a layered extrusion
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     And I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialLayerSet"
     And I press "bim.assign_material"
     And I press "bim.enable_editing_assigned_material"
@@ -222,7 +222,7 @@ Scenario: Update representation - updating a profiled extrusion
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     And I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialProfileSet"
     And I press "bim.assign_material"
     And I press "bim.enable_editing_assigned_material"
@@ -357,7 +357,7 @@ Scenario: Override duplicate move - copying a layered extrusion
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     And I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialLayerSet"
     And I press "bim.assign_material"
     And I press "bim.enable_editing_assigned_material"
@@ -386,7 +386,7 @@ Scenario: Override duplicate move - copying a profiled extrusion
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     And I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialProfileSet"
     And I press "bim.assign_material"
     And I press "bim.enable_editing_assigned_material"
diff --git a/src/blenderbim/test/bim/feature/material.feature b/src/blenderbim/test/bim/feature/material.feature
index 6516cb5c9a..125369586d 100644
--- a/src/blenderbim/test/bim/feature/material.feature
+++ b/src/blenderbim/test/bim/feature/material.feature
@@ -1,9 +1,35 @@
 @material
 Feature: Material
 
+Scenario: Load materials
+    Given an empty IFC project
+    And I press "bim.add_material(obj='')"
+    When I press "bim.load_materials"
+    Then nothing happens
+
+Scenario: Disable editing materials
+    Given an empty IFC project
+    And I press "bim.add_material(obj='')"
+    And I press "bim.load_materials"
+    When I press "bim.disable_editing_materials"
+    Then nothing happens
+
+Scenario: Load materials - then add material
+    Given an empty IFC project
+    And I press "bim.load_materials"
+    When I press "bim.add_material(obj='')"
+    Then the material "Default" exists
+
+Scenario: Load materials - then add material set
+    Given an empty IFC project
+    And I set "scene.BIMMaterialProperties.material_type" to "IfcMaterialLayerSet"
+    And I press "bim.load_materials"
+    When I press "bim.add_material_set(set_type='IfcMaterialLayerSet')"
+    Then nothing happens
+
 Scenario: Add default material
     Given an empty IFC project
-    When I press "bim.add_default_material"
+    When I press "bim.add_material(obj='')"
     Then the material "Default" exists
 
 Scenario: Add material
@@ -11,7 +37,7 @@ Scenario: Add material
     And I add a cube
     And the object "Cube" is selected
     And I add a material
-    When I press "bim.add_material"
+    When I press "bim.add_material(obj='Material')"
     Then the material "Material" is an IFC material
 
 Scenario: Remove material
@@ -19,16 +45,26 @@ Scenario: Remove material
     And I add a cube
     And the object "Cube" is selected
     And I add a material
-    And I press "bim.add_material"
-    When I press "bim.remove_material"
-    Then the material "Material" is not an IFC material
+    And I press "bim.add_material(obj='Material')"
+    And the variable "material" is "{ifc}.by_type('IfcMaterial')[0].id()"
+    When I press "bim.remove_material(material={material})"
+    Then the material "Material" does not exist
+
+Scenario: Remove material set
+    Given an empty IFC project
+    And I set "scene.BIMMaterialProperties.material_type" to "IfcMaterialLayerSet"
+    And I press "bim.load_materials"
+    And I press "bim.add_material_set(set_type='IfcMaterialLayerSet')"
+    And the variable "material" is "{ifc}.by_type('IfcMaterialLayerSet')[0].id()"
+    When I press "bim.remove_material_set(material={material})"
+    Then nothing happens
 
 Scenario: Unlink material
     Given an empty IFC project
     And I add a cube
     And the object "Cube" is selected
     And I add a material
-    And I press "bim.add_material"
+    And I press "bim.add_material(obj='Material')"
     When I press "bim.unlink_material"
     Then the material "Material" is not an IFC material
 
@@ -38,7 +74,7 @@ Scenario: Assign material - Assign a material
     And the object "Cube" is selected
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWall"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     When I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterial"
     And I press "bim.assign_material"
     Then the object "IfcWall/Cube" has the material "Default"
@@ -54,7 +90,7 @@ Scenario: Assign material - Assign a material layer set
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     When I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialLayerSet"
     And I press "bim.assign_material"
     Then nothing happens
@@ -70,7 +106,15 @@ Scenario: Assign material - Assign a material profile set
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     When I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialProfileSet"
     And I press "bim.assign_material"
     Then nothing happens
+
+Scenario: Select by material
+    Given an empty IFC project
+    And I press "bim.load_materials"
+    And I press "bim.add_material(obj='')"
+    And the variable "material" is "{ifc}.by_type('IfcMaterial')[0].id()"
+    When I press "bim.select_by_material(material={material})"
+    Then nothing happens
diff --git a/src/blenderbim/test/bim/feature/model.feature b/src/blenderbim/test/bim/feature/model.feature
index 4a22b908c1..49b85e9641 100644
--- a/src/blenderbim/test/bim/feature/model.feature
+++ b/src/blenderbim/test/bim/feature/model.feature
@@ -40,7 +40,7 @@ Scenario: Add type instance - add a mesh where existing instances have changed c
     And I press "bim.add_type_instance"
     And the object "IfcWall/Wall" data is a "Tessellation" representation of "Model/Body/MODEL_VIEW"
     And the object "IfcWall/Wall" is selected
-    And the variable "context" is "{ifc}.by_type('IfcGeometricRepresentationSubContext')[-1].id()"
+    And the variable "context" is "[c for c in {ifc}.by_type('IfcGeometricRepresentationSubContext') if c.TargetView == 'PLAN_VIEW'][0].id()"
     And I set "scene.BIMRootProperties.contexts" to "{context}"
     And I press "bim.add_representation"
     And the object "IfcWall/Wall" data is a "Annotation2D" representation of "Plan/Annotation/PLAN_VIEW"
diff --git a/src/blenderbim/test/bim/feature/root.feature b/src/blenderbim/test/bim/feature/root.feature
index e9477fe668..6d3bc39226 100644
--- a/src/blenderbim/test/bim/feature/root.feature
+++ b/src/blenderbim/test/bim/feature/root.feature
@@ -43,7 +43,7 @@ Scenario: Assign a class to a cube
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWall"
     And I press "bim.assign_class"
     Then the object "IfcWall/Cube" is an "IfcWall"
-    And the object "IfcWall/Cube" is in the collection "IfcProject/My Project"
+    And the object "IfcWall/Cube" is in the collection "IfcBuildingStorey/My Storey"
     And the object "IfcWall/Cube" has a "Tessellation" representation of "Model/Body/MODEL_VIEW"
 
 Scenario: Assign a type class to a cube
diff --git a/src/blenderbim/test/bim/feature/sequence.feature b/src/blenderbim/test/bim/feature/sequence.feature
index 5f1a2925d6..f2f12e8a2d 100644
--- a/src/blenderbim/test/bim/feature/sequence.feature
+++ b/src/blenderbim/test/bim/feature/sequence.feature
@@ -79,7 +79,7 @@ Scenario: Animate the construction of a wall
     Then "scene.objects.get('IfcWall/Cube').hide_viewport" is "False"
     And "scene.objects.get('IfcWall/Cube').hide_render" is "False"
     And "scene.objects.get('IfcWall/Cube').color" is "[0.0, 1.0, 0.0, 1]"
-    When I am on frame "6"
+    When I am on frame "7"
     Then "scene.objects.get('IfcWall/Cube').color" is "[1.0, 1.0, 1.0, 1]"
 
 Scenario: Animate the demolition of a wall
@@ -116,7 +116,7 @@ Scenario: Animate the demolition of a wall
     Then "scene.objects.get('IfcWall/Cube').hide_viewport" is "False"
     And "scene.objects.get('IfcWall/Cube').hide_render" is "False"
     And "scene.objects.get('IfcWall/Cube').color" is "[1.0, 0.0, 0.0, 1]"
-    When I am on frame "6"
+    When I am on frame "7"
     Then "scene.objects.get('IfcWall/Cube').hide_viewport" is "True"
     And "scene.objects.get('IfcWall/Cube').hide_render" is "True"
     And "scene.objects.get('IfcWall/Cube').color" is "[0.0, 0.0, 0.0, 1]"
@@ -151,7 +151,7 @@ Scenario: Animate the operation of a wall
     Then "scene.objects.get('IfcWall/Cube').color" is "[1.0, 1.0, 1.0, 1]"
     When I am on frame "2"
     Then "scene.objects.get('IfcWall/Cube').color" is "[0.0, 0.0, 1.0, 1]"
-    When I am on frame "6"
+    When I am on frame "7"
     Then "scene.objects.get('IfcWall/Cube').color" is "[1.0, 1.0, 1.0, 1]"
 
 Scenario: Animate the movement of a wall
@@ -200,7 +200,7 @@ Scenario: Animate the movement of a wall
     And "scene.objects.get('IfcWall/ToObject').color" is "[1.0, 1.0, 0.0, 1]"
     And "scene.objects.get('IfcWall/ToObject').hide_viewport" is "False"
     And "scene.objects.get('IfcWall/ToObject').hide_render" is "False"
-    When I am on frame "6"
+    When I am on frame "7"
     Then "scene.objects.get('IfcWall/FromObject').color" is "[0.0, 0.0, 0.0, 1]"
     Then "scene.objects.get('IfcWall/FromObject').hide_viewport" is "True"
     Then "scene.objects.get('IfcWall/FromObject').hide_render" is "True"
@@ -239,7 +239,7 @@ Scenario: Animate the consumption of a wall
     Then "scene.objects.get('IfcWall/Cube').color" is "[0.0, 1.0, 1.0, 1]"
     And "scene.objects.get('IfcWall/Cube').hide_viewport" is "False"
     And "scene.objects.get('IfcWall/Cube').hide_render" is "False"
-    When I am on frame "6"
+    When I am on frame "7"
     Then "scene.objects.get('IfcWall/Cube').color" is "[0.0, 0.0, 0.0, 1]"
     Then "scene.objects.get('IfcWall/Cube').hide_viewport" is "True"
     Then "scene.objects.get('IfcWall/Cube').hide_render" is "True"
diff --git a/src/blenderbim/test/bim/feature/style.feature b/src/blenderbim/test/bim/feature/style.feature
index 2c861f6003..66ad775f2e 100644
--- a/src/blenderbim/test/bim/feature/style.feature
+++ b/src/blenderbim/test/bim/feature/style.feature
@@ -14,7 +14,8 @@ Scenario: Remove style
     And I add a cube
     And I add a material
     And I press "bim.add_style"
-    When I press "bim.remove_style"
+    And the variable "style" is "{ifc}.by_type('IfcSurfaceStyle')[0].id()"
+    When I press "bim.remove_style(style={style})"
     Then nothing happens
 
 Scenario: Add style
@@ -57,3 +58,20 @@ Scenario: Edit style
     And I press "bim.enable_editing_style"
     When I press "bim.edit_style"
     Then nothing happens
+
+Scenario: Load styles
+    Given an empty IFC project
+    And I add a cube
+    And I add a material
+    And I press "bim.add_style"
+    When I press "bim.load_styles(style_type='IfcSurfaceStyle')"
+    Then nothing happens
+
+Scenario: Disable editing styles
+    Given an empty IFC project
+    And I add a cube
+    And I add a material
+    And I press "bim.add_style"
+    And I press "bim.load_styles(style_type='IfcSurfaceStyle')"
+    When I press "bim.disable_editing_style"
+    Then nothing happens
diff --git a/src/blenderbim/test/bim/feature/type.feature b/src/blenderbim/test/bim/feature/type.feature
index 2161090f26..bcde86e305 100644
--- a/src/blenderbim/test/bim/feature/type.feature
+++ b/src/blenderbim/test/bim/feature/type.feature
@@ -42,7 +42,7 @@ Scenario: Assign type - assign to a type with a material layer set
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     And I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialLayerSet"
     And I press "bim.assign_material"
     And I press "bim.enable_editing_assigned_material"
@@ -68,7 +68,7 @@ Scenario: Assign type - assign to a type with a material profile set
     And I set "scene.BIMRootProperties.ifc_product" to "IfcElementType"
     And I set "scene.BIMRootProperties.ifc_class" to "IfcWallType"
     And I press "bim.assign_class"
-    And I press "bim.add_default_material"
+    And I press "bim.add_material(obj='')"
     And I set "active_object.BIMObjectMaterialProperties.material_type" to "IfcMaterialProfileSet"
     And I press "bim.assign_material"
     And I press "bim.enable_editing_assigned_material"
diff --git a/src/blenderbim/test/bim/feature/unit.feature b/src/blenderbim/test/bim/feature/unit.feature
index ec6cd50019..e8d686b50a 100644
--- a/src/blenderbim/test/bim/feature/unit.feature
+++ b/src/blenderbim/test/bim/feature/unit.feature
@@ -50,6 +50,16 @@ Scenario: Add context dependent unit
     When I press "bim.add_context_dependent_unit(name='THINGAMAJIGS', unit_type='LENGTHUNIT')"
     Then nothing happens
 
+Scenario: Add conversion based unit
+    Given an empty IFC project
+    When I press "bim.add_conversion_based_unit(name='inch')"
+    Then nothing happens
+
+Scenario: Add conversion based unit with offset
+    Given an empty IFC project
+    When I press "bim.add_conversion_based_unit(name='fahrenheit')"
+    Then nothing happens
+
 Scenario: Enable editing unit
     Given an empty IFC project
     And the variable "unit" is "{ifc}.by_type('IfcSIUnit')[0].id()"
diff --git a/src/blenderbim/test/bim/test_feature.py b/src/blenderbim/test/bim/test_feature.py
index c28da88105..4cd6dbcd5a 100644
--- a/src/blenderbim/test/bim/test_feature.py
+++ b/src/blenderbim/test/bim/test_feature.py
@@ -297,6 +297,11 @@ def the_material_name_exists(name) -> bpy.types.Material:
     return obj
 
 
+@then(parsers.parse('the material "{name}" does not exist'))
+def the_material_name_does_not_exist(name):
+    assert bpy.data.materials.get(name) is None, "Material exists"
+
+
 @then("an IFC file does not exist")
 def an_ifc_file_does_not_exist():
     ifc = IfcStore.get_file()
diff --git a/src/blenderbim/test/core/test_document.py b/src/blenderbim/test/core/test_document.py
index cbd9ed3e01..708c899e48 100644
--- a/src/blenderbim/test/core/test_document.py
+++ b/src/blenderbim/test/core/test_document.py
@@ -21,20 +21,23 @@ import blenderbim.core.document as subject
 from test.core.bootstrap import ifc, document
 
 
-class TestLoadInformation:
+class TestLoadProjectDocuments:
     def test_run(self, document):
-        document.import_information().should_be_called()
-        document.enable_information_editing_ui().should_be_called()
-        document.disable_editing_document().should_be_called()
-        subject.load_information(document)
+        document.clear_document_tree().should_be_called()
+        document.import_project_documents().should_be_called()
+        document.clear_breadcrumbs().should_be_called()
+        document.enable_editing_ui().should_be_called()
+        subject.load_project_documents(document)
 
 
-class TestLoadReferences:
+class TestLoadDocument:
     def test_run(self, document):
-        document.import_references().should_be_called()
-        document.enable_reference_editing_ui().should_be_called()
+        document.clear_document_tree().should_be_called()
+        document.import_subdocuments("document").should_be_called()
+        document.import_references("document").should_be_called()
         document.disable_editing_document().should_be_called()
-        subject.load_references(document)
+        document.add_breadcrumb("document").should_be_called()
+        subject.load_document(document, document="document")
 
 
 class TestDisableDocumentEditingUi:
@@ -58,72 +61,76 @@ class TestDisableEditingDocument:
 
 
 class TestAddInformation:
-    def test_run(self, ifc, document):
-        ifc.run("document.add_information").should_be_called().will_return("information")
-        document.import_information().should_be_called()
-        document.import_document_attributes("information").should_be_called()
-        document.set_active_document("information").should_be_called()
+    def test_add_and_reload_tree_at_project_root(self, ifc, document):
+        document.clear_document_tree().should_be_called()
+        document.get_active_breadcrumb().should_be_called().will_return(None)
+        ifc.run("document.add_information", parent=None).should_be_called().will_return("information")
+        ifc.run("document.add_reference", information="information").should_be_called()
+        document.import_project_documents().should_be_called()
+        subject.add_information(ifc, document)
+
+    def test_add_and_reload_tree_at_current_parent(self, ifc, document):
+        document.clear_document_tree().should_be_called()
+        document.get_active_breadcrumb().should_be_called().will_return("parent")
+        ifc.run("document.add_information", parent="parent").should_be_called().will_return("information")
+        ifc.run("document.add_reference", information="information").should_be_called()
+        document.import_subdocuments("parent").should_be_called()
+        document.import_references("parent").should_be_called()
         subject.add_information(ifc, document)
 
 
 class TestAddReference:
     def test_run(self, ifc, document):
-        ifc.run("document.add_reference").should_be_called().will_return("reference")
-        document.import_references().should_be_called()
-        document.import_document_attributes("reference").should_be_called()
-        document.set_active_document("reference").should_be_called()
+        document.get_active_breadcrumb().should_be_called().will_return("parent")
+        ifc.run("document.add_reference", information="parent").should_be_called()
+        document.clear_document_tree().should_be_called()
+        document.import_subdocuments("parent").should_be_called()
+        document.import_references("parent").should_be_called()
         subject.add_reference(ifc, document)
 
 
-class TestEditInformation:
-    def test_run(self, ifc, document):
+class TestEditDocument:
+    def test_edit_information(self, ifc, document):
         document.export_document_attributes().should_be_called().will_return("attributes")
-        ifc.run("document.edit_information", information="information", attributes="attributes").should_be_called()
+        document.is_document_information("document").should_be_called().will_return(True)
+        ifc.run("document.edit_information", information="document", attributes="attributes").should_be_called()
         document.disable_editing_document().should_be_called()
-        document.import_information().should_be_called()
-        subject.edit_information(ifc, document, information="information")
+        document.clear_document_tree().should_be_called()
+        document.get_active_breadcrumb().should_be_called().will_return(None)
+        document.import_project_documents().should_be_called()
+        subject.edit_document(ifc, document, document="document")
 
-
-class TestEditInformation:
-    def test_run(self, ifc, document):
+    def test_edit_reference(self, ifc, document):
         document.export_document_attributes().should_be_called().will_return("attributes")
-        ifc.run("document.edit_reference", reference="reference", attributes="attributes").should_be_called()
+        document.is_document_information("document").should_be_called().will_return(False)
+        ifc.run("document.edit_reference", reference="document", attributes="attributes").should_be_called()
         document.disable_editing_document().should_be_called()
-        document.import_references().should_be_called()
-        subject.edit_reference(ifc, document, reference="reference")
+        document.clear_document_tree().should_be_called()
+        document.get_active_breadcrumb().should_be_called().will_return("parent")
+        document.import_subdocuments("parent").should_be_called()
+        document.import_references("parent").should_be_called()
+        subject.edit_document(ifc, document, document="document")
 
 
 class TestRemoveDocument:
     def test_remove_information(self, ifc, document):
+        document.clear_document_tree().should_be_called()
         document.is_document_information("document").should_be_called().will_return(True)
-        ifc.run("document.remove_document", document="document").should_be_called()
-        document.import_information().should_be_called()
-        document.disable_editing_document().should_be_called()
+        ifc.run("document.remove_information", information="document").should_be_called()
+        document.get_active_breadcrumb().should_be_called().will_return(None)
+        document.import_project_documents().should_be_called()
         subject.remove_document(ifc, document, document="document")
 
     def test_remove_reference(self, ifc, document):
+        document.clear_document_tree().should_be_called()
         document.is_document_information("document").should_be_called().will_return(False)
-        ifc.run("document.remove_document", document="document").should_be_called()
-        document.import_references().should_be_called()
-        document.disable_editing_document().should_be_called()
+        ifc.run("document.remove_reference", reference="document").should_be_called()
+        document.get_active_breadcrumb().should_be_called().will_return("parent")
+        document.import_subdocuments("parent").should_be_called()
+        document.import_references("parent").should_be_called()
         subject.remove_document(ifc, document, document="document")
 
 
-class TestEnableAssigningDocument:
-    def test_run(self, document):
-        document.import_references().should_be_called()
-        document.enable_reference_editing_ui().should_be_called()
-        document.disable_editing_document().should_be_called()
-        document.enable_document_assignment_ui("obj").should_be_called()
-        subject.enable_assigning_document(document, obj="obj")
-
-
-class TestDisableAssigningDocument:
-    def test_run(self, document):
-        document.disable_document_assignment_ui("obj").should_be_called()
-        subject.disable_assigning_document(document, obj="obj")
-
-
 class TestAssignDocument:
     def test_run(self, ifc):
         ifc.run("document.assign_document", product="product", document="document").should_be_called()
diff --git a/src/blenderbim/test/core/test_drawing.py b/src/blenderbim/test/core/test_drawing.py
index 5fb7b822fa..a18d3fa140 100644
--- a/src/blenderbim/test/core/test_drawing.py
+++ b/src/blenderbim/test/core/test_drawing.py
@@ -141,7 +141,8 @@ class TestDisableEditingDrawings:
 
 class TestAddDrawing:
     def test_run(self, ifc, collector, drawing):
-        drawing.ensure_unique_drawing_name("UNTITLED").should_be_called().will_return("name")
+        drawing.generate_drawing_name("target_view", "location_hint").should_be_called().will_return("drawing_name")
+        drawing.ensure_unique_drawing_name("drawing_name").should_be_called().will_return("name")
         drawing.generate_drawing_matrix("target_view", "location_hint").should_be_called().will_return("matrix")
         drawing.create_camera("name", "matrix").should_be_called().will_return("obj")
         drawing.get_body_context().should_be_called().will_return("context")
diff --git a/src/blenderbim/test/core/test_material.py b/src/blenderbim/test/core/test_material.py
index a35a2fbf6e..e589c55357 100644
--- a/src/blenderbim/test/core/test_material.py
+++ b/src/blenderbim/test/core/test_material.py
@@ -17,7 +17,7 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import blenderbim.core.material as subject
-from test.core.bootstrap import ifc, material
+from test.core.bootstrap import ifc, material, style
 
 
 class TestUnlinkMaterial:
@@ -26,9 +26,131 @@ class TestUnlinkMaterial:
         subject.unlink_material(ifc, obj="obj")
 
 
-class TestAddDefaultMaterial:
-    def test_run(self, ifc, material):
+class TestAddMaterial:
+    def test_add_a_default_material(self, ifc, material, style):
         material.add_default_material_object().should_be_called().will_return("obj")
-        ifc.run("material.add_material", name="Default").should_be_called().will_return("material")
+        material.get_name("obj").should_be_called().will_return("name")
+        ifc.run("material.add_material", name="name").should_be_called().will_return("material")
         ifc.link("material", "obj").should_be_called()
-        assert subject.add_default_material(ifc, material) == "obj"
+        style.get_style("obj").should_be_called().will_return(None)
+        material.is_editing_materials().should_be_called().will_return(False)
+        assert subject.add_material(ifc, material, style) == "material"
+
+    def test_add_a_material_to_a_blender_material_object(self, ifc, material, style):
+        material.get_name("obj").should_be_called().will_return("name")
+        ifc.run("material.add_material", name="name").should_be_called().will_return("material")
+        ifc.link("material", "obj").should_be_called()
+        style.get_style("obj").should_be_called().will_return(None)
+        material.is_editing_materials().should_be_called().will_return(False)
+        assert subject.add_material(ifc, material, style, obj="obj") == "material"
+
+    def test_reloading_imported_materials_if_you_are_editing_scene_materials(self, ifc, material, style):
+        material.get_name("obj").should_be_called().will_return("name")
+        ifc.run("material.add_material", name="name").should_be_called().will_return("material")
+        ifc.link("material", "obj").should_be_called()
+        style.get_style("obj").should_be_called().will_return(None)
+        material.is_editing_materials().should_be_called().will_return(True)
+        material.get_active_material_type().should_be_called().will_return("material_type")
+        material.import_material_definitions("material_type").should_be_called()
+        assert subject.add_material(ifc, material, style, obj="obj") == "material"
+
+    def test_add_a_style_to_the_material_if_the_object_also_has_an_attached_style(self, ifc, material, style):
+        material.get_name("obj").should_be_called().will_return("name")
+        ifc.run("material.add_material", name="name").should_be_called().will_return("material")
+        ifc.link("material", "obj").should_be_called()
+        style.get_style("obj").should_be_called().will_return("style")
+        style.get_context("obj").should_be_called().will_return("context")
+        ifc.run("style.assign_material_style", material="material", style="style", context="context").should_be_called()
+        material.is_editing_materials().should_be_called().will_return(False)
+        assert subject.add_material(ifc, material, style, obj="obj") == "material"
+
+    def test_not_adding_a_style_if_there_is_no_style_context_available(self, ifc, material, style):
+        material.get_name("obj").should_be_called().will_return("name")
+        ifc.run("material.add_material", name="name").should_be_called().will_return("material")
+        ifc.link("material", "obj").should_be_called()
+        style.get_style("obj").should_be_called().will_return("style")
+        style.get_context("obj").should_be_called().will_return(None)
+        material.is_editing_materials().should_be_called().will_return(False)
+        assert subject.add_material(ifc, material, style, obj="obj") == "material"
+
+
+class TestAddMaterialSet:
+    def test_adding_a_material_set(self, ifc, material):
+        ifc.run("material.add_material_set", name="Unnamed", set_type="set_type").should_be_called().will_return(
+            "material"
+        )
+        material.is_editing_materials().should_be_called().will_return(False)
+        assert subject.add_material_set(ifc, material, set_type="set_type") == "material"
+
+    def test_adding_a_material_set_and_reloading_imported_materials(self, ifc, material):
+        ifc.run("material.add_material_set", name="Unnamed", set_type="set_type").should_be_called().will_return(
+            "material"
+        )
+        material.is_editing_materials().should_be_called().will_return(True)
+        material.get_active_material_type().should_be_called().will_return("material_type")
+        material.import_material_definitions("material_type").should_be_called()
+        assert subject.add_material_set(ifc, material, set_type="set_type") == "material"
+
+
+class TestRemoveMaterial:
+    def test_removing_a_material(self, ifc, material, style):
+        ifc.get_object("material").should_be_called().will_return(None)
+        ifc.unlink(element="material").should_be_called()
+        ifc.run("material.remove_material", material="material").should_be_called()
+        material.is_editing_materials().should_be_called().will_return(False)
+        subject.remove_material(ifc, material, style, material="material")
+
+    def test_removing_a_material_and_reloading_imported_materials(self, ifc, material, style):
+        ifc.get_object("material").should_be_called().will_return(None)
+        ifc.unlink(element="material").should_be_called()
+        ifc.run("material.remove_material", material="material").should_be_called()
+        material.is_editing_materials().should_be_called().will_return(True)
+        material.get_active_material_type().should_be_called().will_return("material_type")
+        material.import_material_definitions("material_type").should_be_called()
+        subject.remove_material(ifc, material, style, material="material")
+
+    def test_removing_a_material_object_if_it_has_no_style(self, ifc, material, style):
+        ifc.get_object("material").should_be_called().will_return("obj")
+        ifc.unlink(element="material").should_be_called()
+        ifc.run("material.remove_material", material="material").should_be_called()
+        style.get_style("obj").should_be_called().will_return(None)
+        material.delete_object("obj").should_be_called()
+        material.is_editing_materials().should_be_called().will_return(False)
+        subject.remove_material(ifc, material, style, material="material")
+
+    def test_preserving_a_material_object_if_it_is_still_used_as_a_style(self, ifc, material, style):
+        ifc.get_object("material").should_be_called().will_return("obj")
+        ifc.unlink(element="material").should_be_called()
+        ifc.run("material.remove_material", material="material").should_be_called()
+        style.get_style("obj").should_be_called().will_return("style")
+        material.is_editing_materials().should_be_called().will_return(False)
+        subject.remove_material(ifc, material, style, material="material")
+
+
+class TestRemoveMaterialSet:
+    def test_run(self, ifc, material):
+        ifc.run("material.remove_material_set", material="material").should_be_called()
+        material.is_editing_materials().should_be_called().will_return(True)
+        material.get_active_material_type().should_be_called().will_return("material_type")
+        material.import_material_definitions("material_type").should_be_called()
+        subject.remove_material_set(ifc, material, material="material")
+
+
+class TestLoadMaterials:
+    def test_run(self, material):
+        material.import_material_definitions("material_type").should_be_called()
+        material.enable_editing_materials().should_be_called()
+        subject.load_materials(material, "material_type")
+
+
+class TestDisableEditingMaterials:
+    def test_run(self, material):
+        material.disable_editing_materials().should_be_called()
+        subject.disable_editing_materials(material)
+
+
+class TestSelectByMaterial:
+    def test_run(self, material):
+        material.get_elements_by_material("material").should_be_called().will_return("elements")
+        material.select_elements("elements").should_be_called()
+        subject.select_by_material(material, material="material")
diff --git a/src/blenderbim/test/core/test_style.py b/src/blenderbim/test/core/test_style.py
index 25e761a3dd..c11b7fec20 100644
--- a/src/blenderbim/test/core/test_style.py
+++ b/src/blenderbim/test/core/test_style.py
@@ -17,7 +17,7 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import blenderbim.core.style as subject
-from test.core.bootstrap import ifc, style
+from test.core.bootstrap import ifc, material, style
 
 
 class TestAddStyle:
@@ -53,11 +53,32 @@ class TestAddStyle:
 
 
 class TestRemoveStyle:
-    def test_run(self, ifc, style):
-        style.get_style("obj").should_be_called().will_return("style")
+    def test_removing_a_style(self, ifc, material, style):
+        ifc.get_object("style").should_be_called().will_return("obj")
         ifc.unlink(obj="obj", element="style").should_be_called()
         ifc.run("style.remove_style", style="style").should_be_called()
-        subject.remove_style(ifc, style, obj="obj")
+        ifc.get_entity("obj").should_be_called().will_return("material")
+        style.is_editing_styles().should_be_called().will_return(False)
+        subject.remove_style(ifc, material, style, style="style")
+
+    def test_removing_a_style_and_reloading_imported_styles(self, ifc, material, style):
+        ifc.get_object("style").should_be_called().will_return("obj")
+        ifc.unlink(obj="obj", element="style").should_be_called()
+        ifc.run("style.remove_style", style="style").should_be_called()
+        ifc.get_entity("obj").should_be_called().will_return("material")
+        style.is_editing_styles().should_be_called().will_return(True)
+        style.get_active_style_type().should_be_called().will_return("style_type")
+        style.import_presentation_styles("style_type").should_be_called()
+        subject.remove_style(ifc, material, style, style="style")
+
+    def test_removing_an_object_if_it_is_not_still_used_for_a_material(self, ifc, material, style):
+        ifc.get_object("style").should_be_called().will_return("obj")
+        ifc.unlink(obj="obj", element="style").should_be_called()
+        ifc.run("style.remove_style", style="style").should_be_called()
+        ifc.get_entity("obj").should_be_called().will_return(None)
+        material.delete_object("obj").should_be_called()
+        style.is_editing_styles().should_be_called().will_return(False)
+        subject.remove_style(ifc, material, style, style="style")
 
 
 class TestUpdateStyleColours:
@@ -174,3 +195,16 @@ class TestEditStyle:
         ifc.run("style.edit_presentation_style", style="style", attributes="attributes").should_be_called()
         style.disable_editing("obj").should_be_called()
         subject.edit_style(ifc, style, obj="obj")
+
+
+class TestLoadStyles:
+    def test_run(self, style):
+        style.import_presentation_styles("style_type").should_be_called()
+        style.enable_editing_styles().should_be_called()
+        subject.load_styles(style, style_type="style_type")
+
+
+class TestDisableEditingStyles:
+    def test_run(self, style):
+        style.disable_editing_styles().should_be_called()
+        subject.disable_editing_styles(style)
diff --git a/src/blenderbim/test/core/test_unit.py b/src/blenderbim/test/core/test_unit.py
index 9cc837b7e8..5c7143ceaa 100644
--- a/src/blenderbim/test/core/test_unit.py
+++ b/src/blenderbim/test/core/test_unit.py
@@ -39,7 +39,9 @@ class TestAssignSceneUnits:
             "unit.add_si_unit", unit_type="VOLUMEUNIT", name="name", prefix="prefix"
         ).should_be_called().will_return("volumeunit")
 
-        ifc.run("unit.assign_unit", units=["lengthunit", "areaunit", "volumeunit"]).should_be_called()
+        ifc.run("unit.add_conversion_based_unit", name="degree").should_be_called().will_return("planeangleunit")
+
+        ifc.run("unit.assign_unit", units=["lengthunit", "areaunit", "volumeunit", "planeangleunit"]).should_be_called()
         subject.assign_scene_units(ifc, unit)
 
     def test_creating_and_assigning_imperial_units(self, ifc, unit):
@@ -53,7 +55,9 @@ class TestAssignSceneUnits:
         unit.get_scene_unit_name("volume").should_be_called().will_return("volumename")
         ifc.run("unit.add_conversion_based_unit", name="volumename").should_be_called().will_return("volumeunit")
 
-        ifc.run("unit.assign_unit", units=["lengthunit", "areaunit", "volumeunit"]).should_be_called()
+        ifc.run("unit.add_conversion_based_unit", name="degree").should_be_called().will_return("planeangleunit")
+
+        ifc.run("unit.assign_unit", units=["lengthunit", "areaunit", "volumeunit", "planeangleunit"]).should_be_called()
         subject.assign_scene_units(ifc, unit)
 
 
@@ -115,6 +119,13 @@ class TestAddContextDependentUnit:
         assert subject.add_context_dependent_unit(ifc, unit, unit_type="unit_type", name="name") == "unit"
 
 
+class TestAddConversionBasedUnit:
+    def test_run(self, ifc, unit):
+        ifc.run("unit.add_conversion_based_unit", name="name").should_be_called().will_return("unit")
+        unit.import_units().should_be_called()
+        assert subject.add_conversion_based_unit(ifc, unit, name="name") == "unit"
+
+
 class TestEnableEditingUnit:
     def test_run(self, unit):
         unit.set_active_unit("unit").should_be_called()
diff --git a/src/blenderbim/test/tool/test_document.py b/src/blenderbim/test/tool/test_document.py
index 8353e5c8f2..3ef56744e0 100644
--- a/src/blenderbim/test/tool/test_document.py
+++ b/src/blenderbim/test/tool/test_document.py
@@ -29,12 +29,30 @@ class TestImplementsTool(NewFile):
         assert isinstance(subject(), blenderbim.core.tool.Document)
 
 
-class TestDisableDocumentAssignmentUI(NewFile):
+class TestAddBreadcrumb(NewFile):
     def test_run(self):
-        obj = bpy.data.objects.new("Object", None)
-        obj.BIMObjectDocumentProperties.is_adding = "foo"
-        subject.disable_document_assignment_ui(obj)
-        assert obj.BIMObjectDocumentProperties.is_adding == ""
+        ifc = ifcopenshell.file()
+        tool.Ifc().set(ifc)
+        document = ifc.createIfcDocumentInformation()
+        subject.add_breadcrumb(document)
+        props = bpy.context.scene.BIMDocumentProperties
+        assert props.breadcrumbs[0].name == str(document.id())
+
+
+class TestClearBreadcrumbs(NewFile):
+    def test_run(self):
+        props = bpy.context.scene.BIMDocumentProperties
+        props.breadcrumbs.add()
+        subject.clear_breadcrumbs()
+        assert len(props.breadcrumbs) == 0
+
+
+class TestClearDocumentTree(NewFile):
+    def test_run(self):
+        props = bpy.context.scene.BIMDocumentProperties
+        new = props.documents.add()
+        subject.clear_document_tree()
+        assert len(props.documents) == 0
 
 
 class TestDisableEditingDocument(NewFile):
@@ -46,31 +64,16 @@ class TestDisableEditingDocument(NewFile):
 
 class TestDisableEditingUI(NewFile):
     def test_run(self):
-        bpy.context.scene.BIMDocumentProperties.is_editing = "is_editing"
+        bpy.context.scene.BIMDocumentProperties.is_editing = True
         subject.disable_editing_ui()
-        assert bpy.context.scene.BIMDocumentProperties.is_editing == ""
+        assert bpy.context.scene.BIMDocumentProperties.is_editing == False
 
 
-class TestEnableDocumentAssignmentUI(NewFile):
+class TestEnableEditingUI(NewFile):
     def test_run(self):
-        obj = bpy.data.objects.new("Object", None)
-        obj.BIMObjectDocumentProperties.is_adding = ""
-        subject.enable_document_assignment_ui(obj)
-        assert obj.BIMObjectDocumentProperties.is_adding == "IfcDocumentReference"
-
-
-class TestEnableInformationEditingUI(NewFile):
-    def test_run(self):
-        bpy.context.scene.BIMDocumentProperties.is_editing = ""
-        subject.enable_information_editing_ui()
-        assert bpy.context.scene.BIMDocumentProperties.is_editing == "information"
-
-
-class TestEnableReferenceEditingUI(NewFile):
-    def test_run(self):
-        bpy.context.scene.BIMDocumentProperties.is_editing = ""
-        subject.enable_reference_editing_ui()
-        assert bpy.context.scene.BIMDocumentProperties.is_editing == "reference"
+        bpy.context.scene.BIMDocumentProperties.is_editing = False
+        subject.enable_editing_ui()
+        assert bpy.context.scene.BIMDocumentProperties.is_editing == True
 
 
 class TestExportDocumentAttributes(NewFile):
@@ -95,6 +98,15 @@ class TestExportDocumentAttributes(NewFile):
         }
 
 
+class TestGetActiveBreadcrumb(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc().set(ifc)
+        document = ifc.createIfcDocumentInformation()
+        subject.add_breadcrumb(document)
+        assert subject.get_active_breadcrumb() == document
+
+
 class TestImportDocumentAttributes(NewFile):
     def test_importing_information(self):
         ifc = ifcopenshell.file()
@@ -149,30 +161,51 @@ class TestImportDocumentAttributes(NewFile):
         assert props.document_attributes.get("Description").string_value == "Description"
 
 
-class TestImportInformation(NewFile):
+class TestImportProjectDocuments(NewFile):
     def test_run(self):
         ifc = ifcopenshell.file()
         tool.Ifc().set(ifc)
-        document = ifc.createIfcDocumentInformation()
-        subject.import_information()
+        ifc.createIfcProject()
+        document = ifcopenshell.api.run("document.add_information", ifc)
+        subject.import_project_documents()
         props = bpy.context.scene.BIMDocumentProperties
         assert len(props.documents) == 1
         assert props.documents[0].ifc_definition_id == document.id()
         assert props.documents[0].name == "Unnamed"
-        assert props.documents[0].identification == "*"
+        assert props.documents[0].identification == "X"
+        assert props.documents[0].is_information is True
 
 
-class TestImportReference(NewFile):
+class TestImportReferences(NewFile):
     def test_run(self):
         ifc = ifcopenshell.file()
         tool.Ifc().set(ifc)
-        document = ifc.createIfcDocumentReference()
-        subject.import_references()
+        ifc.createIfcProject()
+        document = ifcopenshell.api.run("document.add_information", ifc)
+        reference = ifcopenshell.api.run("document.add_reference", ifc, information=document)
+        subject.import_references(document)
         props = bpy.context.scene.BIMDocumentProperties
         assert len(props.documents) == 1
-        assert props.documents[0].ifc_definition_id == document.id()
+        assert props.documents[0].ifc_definition_id == reference.id()
         assert props.documents[0].name == "Unnamed"
         assert props.documents[0].identification == "*"
+        assert props.documents[0].is_information is False
+
+
+class TestImportSubdocuments(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc().set(ifc)
+        ifc.createIfcProject()
+        document = ifcopenshell.api.run("document.add_information", ifc)
+        subdocument = ifcopenshell.api.run("document.add_information", ifc, parent=document)
+        subject.import_subdocuments(document)
+        props = bpy.context.scene.BIMDocumentProperties
+        assert len(props.documents) == 1
+        assert props.documents[0].ifc_definition_id == subdocument.id()
+        assert props.documents[0].name == "Unnamed"
+        assert props.documents[0].identification == "X"
+        assert props.documents[0].is_information is True
 
 
 class TestIsDocumentInformation(NewFile):
@@ -184,6 +217,15 @@ class TestIsDocumentInformation(NewFile):
         assert subject.is_document_information(reference) is False
 
 
+class TestRemoveLatestBreadcrumb(NewFile):
+    def test_run(self):
+        props = bpy.context.scene.BIMDocumentProperties
+        props.breadcrumbs.add()
+        props.breadcrumbs.add()
+        subject.remove_latest_breadcrumb()
+        assert len(props.breadcrumbs) == 1
+
+
 class TestSetActiveDocument(NewFile):
     def test_run(self):
         ifc = ifcopenshell.file()
diff --git a/src/blenderbim/test/tool/test_drawing.py b/src/blenderbim/test/tool/test_drawing.py
index 7680dfff88..91b96f46dd 100644
--- a/src/blenderbim/test/tool/test_drawing.py
+++ b/src/blenderbim/test/tool/test_drawing.py
@@ -399,10 +399,13 @@ class TestImportDrawings(NewFile):
         ifc = ifcopenshell.file()
         tool.Ifc.set(ifc)
         drawing = ifc.createIfcAnnotation(Name="FOOBAR", ObjectType="DRAWING")
+        pset = ifcopenshell.api.run("pset.add_pset", ifc, product=drawing, name="EPset_Drawing")
+        ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"TargetView": "PLAN_VIEW"})
         subject.import_drawings()
         props = bpy.context.scene.DocProperties
         assert props.drawings[0].ifc_definition_id == drawing.id()
         assert props.drawings[0].name == "FOOBAR"
+        assert props.drawings[0].target_view == "PLAN_VIEW"
 
 
 class TestImportSheets(NewFile):
diff --git a/src/blenderbim/test/tool/test_material.py b/src/blenderbim/test/tool/test_material.py
index d8c50c09bf..4ce5af138f 100644
--- a/src/blenderbim/test/tool/test_material.py
+++ b/src/blenderbim/test/tool/test_material.py
@@ -34,3 +34,122 @@ class TestAddDefaultMaterialObject(NewFile):
         material = subject.add_default_material_object()
         assert isinstance(material, bpy.types.Material)
         assert material.name == "Default"
+
+
+class TestDeleteObject(NewFile):
+    def test_run(self):
+        material = subject.add_default_material_object()
+        assert bpy.data.materials.get("Default")
+        subject.delete_object(material)
+        assert not bpy.data.materials.get("Default")
+
+
+class TestDisableEditingMaterials(NewFile):
+    def test_run(self):
+        bpy.context.scene.BIMMaterialProperties.is_editing = True
+        subject.disable_editing_materials()
+        assert bpy.context.scene.BIMMaterialProperties.is_editing is False
+
+
+class TestEnableEditingMaterials(NewFile):
+    def test_run(self):
+        bpy.context.scene.BIMMaterialProperties.is_editing = False
+        subject.enable_editing_materials()
+        assert bpy.context.scene.BIMMaterialProperties.is_editing is True
+
+
+class TestGetActiveMaterialType(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        bpy.context.scene.BIMMaterialProperties.material_type = "IfcMaterial"
+        assert subject.get_active_material_type() == "IfcMaterial"
+        bpy.context.scene.BIMMaterialProperties.material_type = "IfcMaterialLayerSet"
+        assert subject.get_active_material_type() == "IfcMaterialLayerSet"
+
+
+class TestGetElementsByMaterial(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", ifc)
+        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material)
+        assert subject.get_elements_by_material(material) == {element}
+
+
+class TestGetName(NewFile):
+    def test_run(self):
+        assert subject.get_name(bpy.data.materials.new("Material")) == "Material"
+
+
+class TestImportMaterialDefinitions(NewFile):
+    def test_import_materials(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        material = ifc.createIfcMaterial(Name="Name")
+        subject.import_material_definitions("IfcMaterial")
+        props = bpy.context.scene.BIMMaterialProperties
+        assert props.materials[0].ifc_definition_id == material.id()
+        assert props.materials[0].name == "Name"
+        assert props.materials[0].total_elements == 0
+
+    def test_import_material_layer_sets(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        material = ifc.createIfcMaterialLayerSet(LayerSetName="Name")
+        subject.import_material_definitions("IfcMaterialLayerSet")
+        props = bpy.context.scene.BIMMaterialProperties
+        assert props.materials[0].ifc_definition_id == material.id()
+        assert props.materials[0].name == "Name"
+        assert props.materials[0].total_elements == 0
+
+    def test_import_material_profile_sets(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        material = ifc.createIfcMaterialProfileSet(Name="Name")
+        subject.import_material_definitions("IfcMaterialProfileSet")
+        props = bpy.context.scene.BIMMaterialProperties
+        assert props.materials[0].ifc_definition_id == material.id()
+        assert props.materials[0].name == "Name"
+        assert props.materials[0].total_elements == 0
+
+    def test_import_material_constituent_sets(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        material = ifc.createIfcMaterialConstituentSet(Name="Name")
+        subject.import_material_definitions("IfcMaterialConstituentSet")
+        props = bpy.context.scene.BIMMaterialProperties
+        assert props.materials[0].ifc_definition_id == material.id()
+        assert props.materials[0].name == "Name"
+        assert props.materials[0].total_elements == 0
+
+    def test_import_material_lists(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        material = ifc.createIfcMaterialList()
+        subject.import_material_definitions("IfcMaterialList")
+        props = bpy.context.scene.BIMMaterialProperties
+        assert props.materials[0].ifc_definition_id == material.id()
+        assert props.materials[0].name == "Unnamed"
+        assert props.materials[0].total_elements == 0
+
+
+class TestIsEditingMaterials(NewFile):
+    def test_run(self):
+        bpy.context.scene.BIMMaterialProperties.is_editing = False
+        subject.is_editing_materials() is False
+        bpy.context.scene.BIMMaterialProperties.is_editing = True
+        subject.is_editing_materials() is True
+
+
+class TestSelectElements(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc().set(ifc)
+        element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcPump")
+        obj = bpy.data.objects.new("Object", None)
+        bpy.context.scene.collection.objects.link(obj)
+        tool.Ifc.link(element, obj)
+        subject.select_elements([element])
+        assert obj in bpy.context.selected_objects
diff --git a/src/blenderbim/test/tool/test_style.py b/src/blenderbim/test/tool/test_style.py
index b1fc859453..dd39292dc7 100644
--- a/src/blenderbim/test/tool/test_style.py
+++ b/src/blenderbim/test/tool/test_style.py
@@ -50,6 +50,13 @@ class TestDisableEditing(NewFile):
         assert obj.BIMStyleProperties.is_editing is False
 
 
+class TestDisableEditingStyles(NewFile):
+    def test_run(self):
+        bpy.context.scene.BIMStylesProperties.is_editing = True
+        subject.disable_editing_styles()
+        assert bpy.context.scene.BIMStylesProperties.is_editing is False
+
+
 class TestEnableEditing(NewFile):
     def test_run(self):
         obj = bpy.data.materials.new("Material")
@@ -57,6 +64,13 @@ class TestEnableEditing(NewFile):
         assert obj.BIMStyleProperties.is_editing is True
 
 
+class TestEnableEditingStyles(NewFile):
+    def test_run(self):
+        bpy.context.scene.BIMStylesProperties.is_editing = False
+        subject.enable_editing_styles()
+        assert bpy.context.scene.BIMStylesProperties.is_editing is True
+
+
 class TestExportSurfaceAttributes(NewFile):
     def test_run(self):
         TestImportSurfaceAttributes().test_run()
@@ -64,6 +78,16 @@ class TestExportSurfaceAttributes(NewFile):
         assert subject.export_surface_attributes(obj) == {"Name": "Name", "Side": "BOTH"}
 
 
+class TestGetActiveStyleType(NewFile):
+    def test_run(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        bpy.context.scene.BIMStylesProperties.style_type = "IfcSurfaceStyle"
+        assert subject.get_active_style_type() == "IfcSurfaceStyle"
+        bpy.context.scene.BIMStylesProperties.style_type = "IfcCurveStyle"
+        assert subject.get_active_style_type() == "IfcCurveStyle"
+
+
 class TestGetContext(NewFile):
     def test_run(self):
         bpy.ops.bim.create_project()
@@ -116,6 +140,7 @@ class TestGetSurfaceRenderingAttributes(NewFile):
                 "Green": 0.5,
                 "Blue": 0.5,
             },
+            "SpecularColour": 0.0,
             "SpecularHighlight": {"IfcSpecularRoughness": 0.2},
             "ReflectanceMethod": "NOTDEFINED",
         }
@@ -351,3 +376,53 @@ class TestImportSurfaceAttributes(NewFile):
         assert len(obj.BIMStyleProperties.attributes) == 2
         assert obj.BIMStyleProperties.attributes.get("Name").string_value == "Name"
         assert obj.BIMStyleProperties.attributes.get("Side").enum_value == "BOTH"
+
+
+class TestImportPresentationStyles(NewFile):
+    def test_import_curve_styles(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        style = ifc.createIfcCurveStyle(Name="Name")
+        subject.import_presentation_styles("IfcCurveStyle")
+        props = bpy.context.scene.BIMStylesProperties
+        assert props.styles[0].ifc_definition_id == style.id()
+        assert props.styles[0].name == "Name"
+        assert props.styles[0].total_elements == 0
+
+    def test_import_fillarea_styles(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        style = ifc.createIfcFillAreaStyle(Name="Name")
+        subject.import_presentation_styles("IfcFillAreaStyle")
+        props = bpy.context.scene.BIMStylesProperties
+        assert props.styles[0].ifc_definition_id == style.id()
+        assert props.styles[0].name == "Name"
+        assert props.styles[0].total_elements == 0
+
+    def test_import_surface_styles(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        style = ifc.createIfcSurfaceStyle(Name="Name")
+        subject.import_presentation_styles("IfcSurfaceStyle")
+        props = bpy.context.scene.BIMStylesProperties
+        assert props.styles[0].ifc_definition_id == style.id()
+        assert props.styles[0].name == "Name"
+        assert props.styles[0].total_elements == 0
+
+    def test_import_text_styles(self):
+        ifc = ifcopenshell.file()
+        tool.Ifc.set(ifc)
+        style = ifc.createIfcTextStyle(Name="Name")
+        subject.import_presentation_styles("IfcTextStyle")
+        props = bpy.context.scene.BIMStylesProperties
+        assert props.styles[0].ifc_definition_id == style.id()
+        assert props.styles[0].name == "Name"
+        assert props.styles[0].total_elements == 0
+
+
+class TestIsEditingStyles(NewFile):
+    def test_run(self):
+        bpy.context.scene.BIMStylesProperties.is_editing = False
+        subject.is_editing_styles() is False
+        bpy.context.scene.BIMStylesProperties.is_editing = True
+        subject.is_editing_styles() is True
diff --git a/src/ifcgeom/IfcGeom.h b/src/ifcgeom/IfcGeom.h
index cdf3a6414c..687a437c4c 100644
--- a/src/ifcgeom/IfcGeom.h
+++ b/src/ifcgeom/IfcGeom.h
@@ -299,7 +299,7 @@ private:
 
 public:
 	MAKE_TYPE_NAME(Kernel)()
-		: IfcGeom::Kernel(0)
+		: IfcGeom::Kernel()
 		, deflection_tolerance(0.001)
 		, max_faces_to_orient(-1.0)
 		, ifc_length_unit(1.0)
@@ -321,7 +321,7 @@ public:
 	{}
 
 	MAKE_TYPE_NAME(Kernel)(const MAKE_TYPE_NAME(Kernel)& other)
-		: IfcGeom::Kernel(0)
+		: IfcGeom::Kernel()
 		, deflection_tolerance(other.deflection_tolerance)
 		, max_faces_to_orient(other.max_faces_to_orient)
 		, ifc_length_unit(other.ifc_length_unit)
diff --git a/src/ifcgeom/IfcGeomFaces.cpp b/src/ifcgeom/IfcGeomFaces.cpp
index 907f9d1d60..7d2d339282 100644
--- a/src/ifcgeom/IfcGeomFaces.cpp
+++ b/src/ifcgeom/IfcGeomFaces.cpp
@@ -563,8 +563,8 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcRectangleHollowProfileDef* l,
 	const double y = l->YDim() / 2.0f  * getValue(GV_LENGTH_UNIT);
 	const double d = l->WallThickness() * getValue(GV_LENGTH_UNIT);
 
-	const bool fr1 = !l->OuterFilletRadius();
-	const bool fr2 = !l->InnerFilletRadius();
+	const bool fr1 = !!l->OuterFilletRadius();
+	const bool fr2 = !!l->InnerFilletRadius();
 
 	const double r1 = fr1 ? (*l->OuterFilletRadius()) * getValue(GV_LENGTH_UNIT) : 0.;
 	const double r2 = fr2 ? (*l->InnerFilletRadius()) * getValue(GV_LENGTH_UNIT) : 0.;
diff --git a/src/ifcgeom/IfcGeomFunctions.cpp b/src/ifcgeom/IfcGeomFunctions.cpp
index 69e74a8102..88e2bf132a 100644
--- a/src/ifcgeom/IfcGeomFunctions.cpp
+++ b/src/ifcgeom/IfcGeomFunctions.cpp
@@ -4240,6 +4240,7 @@ bool IfcGeom::Kernel::wire_intersections(const TopoDS_Wire& wire, TopTools_ListO
 			  : (std::min)(min_edge_length(wire) / 2., getValue(GV_PRECISION) * 10.);
 	}
 
+	// @todo: should this start from 0 in case of n > 64?
 	for (int i = 2; i < n; ++i) {
 
 		std::vector<int> js;
@@ -5224,8 +5225,11 @@ bool IfcGeom::Kernel::boolean_operation(const TopoDS_Shape& a_input, const TopTo
 							PERF("boolean operation: result min face-face dist check");
 
 							if ((v = min_face_face_distance(r, 1.e-4)) < 1.e-4) {
-								reason = 2;
-								success = false;
+								// #2095 Check if this distance wasn't already realized in the input first operand.
+								if (v < min_face_face_distance(a, 1.e-4)) {
+									reason = 2;
+									success = false;
+								}
 							}
 						}
 
diff --git a/src/ifcgeom/IfcGeomWires.cpp b/src/ifcgeom/IfcGeomWires.cpp
index 93beea10d7..c1bb274c1b 100644
--- a/src/ifcgeom/IfcGeomWires.cpp
+++ b/src/ifcgeom/IfcGeomWires.cpp
@@ -92,7 +92,12 @@
 #include <TopTools_ListIteratorOfListOfShape.hxx>
 
 #include <BRepAdaptor_CompCurve.hxx>
+
+#include <Standard_Version.hxx>
+#if OCC_VERSION_HEX < 0x70600
 #include <BRepAdaptor_HCompCurve.hxx>
+#endif
+
 #include <Approx_Curve3d.hxx>
 
 #include "../ifcgeom/IfcGeom.h"
@@ -483,8 +488,12 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcTrimmedCurve* l, TopoDS_Wire&
 		Logger::Warning("Approximating BasisCurve due to possible discontinuities", l);
 		TopoDS_Wire w;
 		if (!convert_wire(basis_curve, w)) return false;
+#if OCC_VERSION_HEX < 0x70600
 		BRepAdaptor_CompCurve cc(w, true);
 		Handle(Adaptor3d_HCurve) hcc = Handle(Adaptor3d_HCurve)(new BRepAdaptor_HCompCurve(cc));
+#else
+		auto hcc = new BRepAdaptor_CompCurve(w, true);
+#endif
 		// @todo, arbitrary numbers here, note they cannot be too high as contiguous memory is allocated based on them.
 		Approx_Curve3d approx(hcc, getValue(GV_PRECISION), GeomAbs_C0, 10, 10);
 		curve = approx.Curve();
@@ -606,7 +615,10 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcTrimmedCurve* l, TopoDS_Wire&
 			}
 		}
 
-		if (isConic && ALMOST_THE_SAME(fmod(flts[1]-flts[0],M_PI*2.), 0., 100 * getValue(GV_PRECISION) / (2 * M_PI * radius))) {
+		// @todo is 100. not too much? Check with the original issue.
+		const double precision_markup = getValue(IfcGeom::Kernel::GV_PRECISION_FACTOR) == 1. ? 1. : 100.;
+
+		if (isConic && ALMOST_THE_SAME(fmod(flts[1]-flts[0],M_PI*2.), 0., precision_markup * getValue(GV_PRECISION) / (2 * M_PI * radius))) {
 			e = BRepBuilderAPI_MakeEdge(curve).Edge();
 		} else {
 			BRepBuilderAPI_MakeEdge me (curve,flts[0],flts[1]);
@@ -681,6 +693,7 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcPolyline* l, TopoDS_Wire& resu
 		polygon.Append(pnt);
 	}
 
+	// @todo the strict tolerance should also govern these arbitrary precision increases
 	const double eps = getValue(GV_PRECISION) * 10;
 	const bool closed_by_proximity = polygon.Length() >= 3 && polygon.First().Distance(polygon.Last()) < eps;
 	if (closed_by_proximity) {
diff --git a/src/ifcgeom_schema_agnostic/Kernel.h b/src/ifcgeom_schema_agnostic/Kernel.h
index 3aab1e4632..ceb6174755 100644
--- a/src/ifcgeom_schema_agnostic/Kernel.h
+++ b/src/ifcgeom_schema_agnostic/Kernel.h
@@ -42,6 +42,9 @@ namespace IfcGeom {
 	private:
 		Kernel* implementation_;
 
+	protected:
+		Kernel() {};
+
 	public:
 		// Tolerances and settings for various geometrical operations:
 		enum GeomValue {
@@ -80,7 +83,7 @@ namespace IfcGeom {
 			GV_BOOLEAN_ATTEMPT_2D
 		};
 
-		Kernel(IfcParse::IfcFile* file_ = 0);
+		Kernel(IfcParse::IfcFile* file_);
 		
 		virtual ~Kernel() {}
 
diff --git a/src/ifcopenshell-python/ifcopenshell/api/document/add_information.py b/src/ifcopenshell-python/ifcopenshell/api/document/add_information.py
index f4a6cab8ef..d54cede7dc 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/document/add_information.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/document/add_information.py
@@ -22,12 +22,36 @@ import ifcopenshell
 class Usecase:
     def __init__(self, file, **settings):
         self.file = file
-        self.settings = {}
+        self.settings = {"parent": None}
         for key, value in settings.items():
             self.settings[key] = value
 
     def execute(self):
         id_attribute = "DocumentId" if self.file.schema == "IFC2X3" else "Identification"
-        return self.file.create_entity(
-            "IfcDocumentInformation", **{id_attribute: ifcopenshell.guid.new(), "Name": "Unnamed"}
+        information = self.file.create_entity(
+            "IfcDocumentInformation", **{id_attribute: "X", "Name": "Unnamed"}
         )
+        parent = self.settings["parent"]
+        if not parent and self.file.by_type("IfcProject"):
+            parent = self.file.by_type("IfcProject")[0]
+        if parent.is_a("IfcProject") or parent.is_a("IfcContext"):
+            self.file.create_entity(
+                "IfcRelAssociatesDocument",
+                GlobalId=ifcopenshell.guid.new(),
+                OwnerHistory=ifcopenshell.api.run("owner.create_owner_history", self.file),
+                RelatingDocument=information,
+                RelatedObjects=[parent],
+            )
+        elif parent.is_a("IfcDocumentInformation"):
+            if parent.IsPointer:
+                rel = parent.IsPointer[0]
+                documents = set(rel.RelatedDocuments)
+                documents.add(information)
+                rel.RelatedDocuments = list(documents)
+            else:
+                self.file.create_entity(
+                    "IfcDocumentInformationRelationship",
+                    RelatingDocument=parent,
+                    RelatedDocuments=[information]
+                )
+        return information
diff --git a/src/ifcopenshell-python/ifcopenshell/api/document/add_reference.py b/src/ifcopenshell-python/ifcopenshell/api/document/add_reference.py
index 4c02981743..90505d9886 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/document/add_reference.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/document/add_reference.py
@@ -16,16 +16,15 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
-import ifcopenshell
-
 
 class Usecase:
     def __init__(self, file, **settings):
         self.file = file
-        self.settings = {}
+        self.settings = {"information": None}
         for key, value in settings.items():
             self.settings[key] = value
 
     def execute(self):
-        id_attribute = "ItemReference" if self.file.schema == "IFC2X3" else "Identification"
-        return self.file.create_entity("IfcDocumentReference", **{id_attribute: ifcopenshell.guid.new()})
+        if self.file.schema == "IFC2X3":
+            return self.file.create_entity("IfcDocumentReference")
+        return self.file.create_entity("IfcDocumentReference", ReferencedDocument=self.settings["information"])
diff --git a/src/ifcopenshell-python/ifcopenshell/api/document/assign_document.py b/src/ifcopenshell-python/ifcopenshell/api/document/assign_document.py
index ff1f416eb5..c43c2afd3b 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/document/assign_document.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/document/assign_document.py
@@ -56,7 +56,7 @@ class Usecase:
             "IfcRelAssociatesDocument",
             **{
                 "GlobalId": ifcopenshell.guid.new(),
-                # TODO: owner history
+                "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
                 "RelatingDocument": self.settings["document"],
             }
         )
diff --git a/src/ifcopenshell-python/ifcopenshell/api/document/remove_information.py b/src/ifcopenshell-python/ifcopenshell/api/document/remove_information.py
new file mode 100644
index 0000000000..11a0fc6cd4
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/document/remove_information.py
@@ -0,0 +1,39 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import ifcopenshell.api
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"information": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for reference in self.settings["information"].HasDocumentReferences or []:
+            ifcopenshell.api.run("document.remove_reference", self.file, reference=reference)
+        for rel in self.settings["information"].IsPointer or []:
+            for information in rel.RelatedDocuments:
+                ifcopenshell.api.run("document.remove_information", self.file, information=information)
+            self.file.remove(rel)
+        for rel in self.settings["information"].DocumentInfoForObjects or []:
+            self.file.remove(rel)
+        self.file.remove(self.settings["information"])
diff --git a/src/ifcopenshell-python/ifcopenshell/api/document/remove_document.py b/src/ifcopenshell-python/ifcopenshell/api/document/remove_reference.py
similarity index 76%
rename from src/ifcopenshell-python/ifcopenshell/api/document/remove_document.py
rename to src/ifcopenshell-python/ifcopenshell/api/document/remove_reference.py
index b83e9fb560..f4cc669912 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/document/remove_document.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/document/remove_reference.py
@@ -1,5 +1,5 @@
 # IfcOpenShell - IFC toolkit and geometry engine
-# Copyright (C) 2021 Dion Moult <dion@thinkmoult.com>
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
 #
 # This file is part of IfcOpenShell.
 #
@@ -20,12 +20,11 @@
 class Usecase:
     def __init__(self, file, **settings):
         self.file = file
-        self.settings = {"document": None}
+        self.settings = {"reference": None}
         for key, value in settings.items():
             self.settings[key] = value
 
     def execute(self):
-        self.file.remove(self.settings["document"])
-        for rel in self.file.by_type("IfcRelAssociatesDocument"):
-            if not rel.RelatingDocument:
-                self.file.remove(rel)
+        for rel in self.settings["reference"].DocumentRefForObjects or []:
+            self.file.remove(rel)
+        self.file.remove(self.settings["reference"])
diff --git a/src/ifcopenshell-python/ifcopenshell/api/drawing/assign_product.py b/src/ifcopenshell-python/ifcopenshell/api/drawing/assign_product.py
index 913a82e8e5..b41ce3865b 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/drawing/assign_product.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/drawing/assign_product.py
@@ -31,16 +31,32 @@ class Usecase:
             self.settings[key] = value
 
     def execute(self):
-        if self.settings["related_object"].HasAssignments:
-            for assignment in self.settings["related_object"].HasAssignments:
-                if (
-                    assignment.is_a("IfcRelAssignsToProduct")
-                    and assignment.RelatingProduct == self.settings["relating_product"]
-                ):
+        is_grid_axis = self.settings["relating_product"].is_a("IfcGridAxis")
+
+        if is_grid_axis:
+            if self.settings["related_object"].HasAssignments:
+                for rel in self.settings["related_object"].HasAssignments:
+                    if rel.is_a("IfcRelAssignsToProduct") and rel.Name == self.settings["relating_product"].AxisTag:
+                        return
+        elif self.settings["related_object"].HasAssignments:
+            for rel in self.settings["related_object"].HasAssignments:
+                if rel.is_a("IfcRelAssignsToProduct") and rel.RelatingProduct == self.settings["relating_product"]:
                     return
 
         referenced_by = None
-        if self.settings["relating_product"].ReferencedBy:
+
+        if is_grid_axis:
+            axis = self.settings["relating_product"]
+            grid = None
+            for attribute in ("PartOfW", "PartOfV", "PartOfU"):
+                if getattr(axis, attribute, None):
+                    grid = getattr(axis, attribute)[0]
+            self.settings["relating_product"] = grid
+            for rel in grid.ReferencedBy:
+                if rel.Name == axis.AxisTag:
+                    referenced_by = rel
+                    break
+        elif self.settings["relating_product"].ReferencedBy:
             referenced_by = self.settings["relating_product"].ReferencedBy[0]
 
         if referenced_by:
@@ -58,4 +74,7 @@ class Usecase:
                     "RelatingProduct": self.settings["relating_product"],
                 }
             )
+
+        if is_grid_axis:
+            referenced_by.Name = axis.AxisTag
         return referenced_by
diff --git a/src/ifcopenshell-python/ifcopenshell/api/material/add_material_set.py b/src/ifcopenshell-python/ifcopenshell/api/material/add_material_set.py
new file mode 100644
index 0000000000..91bc609bf3
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/material/add_material_set.py
@@ -0,0 +1,32 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"name": "Unnamed", "set_type": "IfcMaterialConstituentSet"}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        if self.settings["set_type"] == "IfcMaterialLayerSet":
+            return self.file.create_entity("IfcMaterialLayerSet", LayerSetName=self.settings["name"] or "Unnamed")
+        elif self.settings["set_type"] == "IfcMaterialList":
+            return self.file.create_entity("IfcMaterialList")
+        return self.file.create_entity(self.settings["set_type"], Name=self.settings["name"] or "Unnamed")
diff --git a/src/ifcopenshell-python/ifcopenshell/api/material/assign_material.py b/src/ifcopenshell-python/ifcopenshell/api/material/assign_material.py
index a5db198ddd..4430c2eb63 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/material/assign_material.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/material/assign_material.py
@@ -124,7 +124,7 @@ class Usecase:
         )
 
     def get_rel_associates_material(self, material):
-        if self.file.schema == "IFC2X3":
+        if self.file.schema == "IFC2X3" or material.is_a("IfcMaterialList"):
             rel = [
                 r
                 for r in self.file.by_type("IfcRelAssociatesMaterial")
diff --git a/src/ifcopenshell-python/ifcopenshell/api/material/remove_material.py b/src/ifcopenshell-python/ifcopenshell/api/material/remove_material.py
index 8213bdd933..bcb71b1da5 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/material/remove_material.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/material/remove_material.py
@@ -29,8 +29,8 @@ class Usecase:
     def execute(self):
         inverse_elements = self.file.get_inverse(self.settings["material"])
         self.file.remove(self.settings["material"])
-        # TODO: this is probably not robust enough
-        # TODO: purge material definition representation
+        # TODO: Right now, we we choose only to delete set items (e.g. a layer) but not the material set
+        # This can lead to invalid material sets, but we assume the user will deal with it
         for inverse in inverse_elements:
             if inverse.is_a("IfcMaterialConstituent"):
                 self.file.remove(inverse)
@@ -40,3 +40,13 @@ class Usecase:
                 self.file.remove(inverse)
             elif inverse.is_a("IfcRelAssociatesMaterial"):
                 self.file.remove(inverse)
+            elif inverse.is_a("IfcMaterialProperties"):
+                for prop in inverse.Properties or []:
+                    self.file.remove(prop)
+                self.file.remove(inverse)
+            elif inverse.is_a("IfcMaterialDefinitionRepresentation"):
+                for representation in inverse.Representations:
+                    for item in representation.Items:
+                        self.file.remove(item)
+                    self.file.remove(representation)
+                self.file.remove(inverse)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/material/remove_material_set.py b/src/ifcopenshell-python/ifcopenshell/api/material/remove_material_set.py
new file mode 100644
index 0000000000..f002b3a9fd
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/material/remove_material_set.py
@@ -0,0 +1,48 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import ifcopenshell
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"material": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        inverse_elements = self.file.get_inverse(self.settings["material"])
+        if self.settings["material"].is_a("IfcMaterialLayerSet"):
+            set_items = self.settings["material"].MaterialLayers or []
+        elif self.settings["material"].is_a("IfcMaterialProfileSet"):
+            set_items = self.settings["material"].MaterialProfiles or []
+        elif self.settings["material"].is_a("IfcMaterialConstituentSet"):
+            set_items = self.settings["material"].MaterialConstituents or []
+        elif self.settings["material"].is_a("IfcMaterialList"):
+            set_items = []
+        for set_item in set_items:
+            self.file.remove(set_item)
+        self.file.remove(self.settings["material"])
+        for inverse in inverse_elements:
+            if inverse.is_a("IfcRelAssociatesMaterial"):
+                self.file.remove(inverse)
+            elif inverse.is_a("IfcMaterialProperties"):
+                for prop in inverse.Properties or []:
+                    self.file.remove(prop)
+                self.file.remove(inverse)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/pset/remove_pset.py b/src/ifcopenshell-python/ifcopenshell/api/pset/remove_pset.py
index 505593d81a..e2d663cf8f 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/pset/remove_pset.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/pset/remove_pset.py
@@ -37,7 +37,12 @@ class Usecase:
                     inverse.RelatedObjects = related_objects
                     should_remove_pset = False
         if should_remove_pset:
+            if self.settings["pset"].is_a("IfcPropertySet"):
+                properties = self.settings["pset"].HasProperties or []
+            elif self.settings["pset"].is_a("IfcQuantitySet"):
+                properties = self.settings["pset"].Quantities or []
+            for prop in properties:
+                self.file.remove(prop)
             self.file.remove(self.settings["pset"])
         for element in to_purge:
             self.file.remove(element)
-        # TODO: implement deep purging
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
index d578cb0c43..99fc616e33 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py
@@ -47,15 +47,32 @@ class Usecase:
 
         for rel in task.IsSuccessorFrom:
             predecessor = rel.RelatingProcess
+            predecessor_duration = (
+                ifcopenshell.util.date.ifc2datetime(predecessor.TaskTime.ScheduleDuration)
+                if predecessor.TaskTime.ScheduleDuration
+                else datetime.timedelta()
+            )
             if rel.SequenceType == "FINISH_START":
                 finish = self.get_task_time_attribute(predecessor, "ScheduleFinish")
                 if not finish:
                     continue
+                days = 0 if predecessor_duration.days == 0 else 1
+                duration_type = "WORKTIME"
                 if rel.TimeLag:
-                    days = self.get_lag_time_days(rel.TimeLag)
+                    days += self.get_lag_time_days(rel.TimeLag)
                     duration_type = rel.TimeLag.DurationType
-                    starts.append(self.offset_date(finish, days, duration_type, self.get_calendar(task)))
-                    starts.append(self.offset_date(finish, days, duration_type, self.get_calendar(predecessor)))
+                if days:
+                    starts.append(
+                        datetime.datetime.combine(
+                            self.offset_date(finish, days, duration_type, self.get_calendar(task)), datetime.time(9)
+                        )
+                    )
+                    starts.append(
+                        datetime.datetime.combine(
+                            self.offset_date(finish, days, duration_type, self.get_calendar(predecessor)),
+                            datetime.time(9),
+                        )
+                    )
                 else:
                     starts.append(finish)
             elif rel.SequenceType == "START_START":
@@ -84,25 +101,31 @@ class Usecase:
                 start = self.get_task_time_attribute(predecessor, "ScheduleStart")
                 if not start:
                     continue
+                days = -1
+                duration_type = "WORKTIME"
                 if rel.TimeLag:
-                    days = self.get_lag_time_days(rel.TimeLag)
+                    days += self.get_lag_time_days(rel.TimeLag)
                     duration_type = rel.TimeLag.DurationType
-                    finishes.append(self.offset_date(start, days, duration_type, self.get_calendar(task)))
-                    finishes.append(self.offset_date(start, days, duration_type, self.get_calendar(predecessor)))
+                if days or rel.TimeLag:
+                    finishes.append(
+                        datetime.datetime.combine(
+                            self.offset_date(start, days, duration_type, self.get_calendar(task)), datetime.time(17)
+                        )
+                    )
+                    finishes.append(
+                        datetime.datetime.combine(
+                            self.offset_date(start, days, duration_type, self.get_calendar(predecessor)),
+                            datetime.time(17),
+                        )
+                    )
                 else:
                     finishes.append(start)
 
         if starts and finishes:
             start = max(starts)
             finish = max(finishes)
-            potential_finish = datetime.datetime.combine(
-                ifcopenshell.util.sequence.get_finish_date(
-                    start,
-                    duration,
-                    task.TaskTime.DurationType,
-                    self.get_calendar(task),
-                ),
-                datetime.datetime.min.time(),
+            potential_finish = ifcopenshell.util.sequence.get_start_or_finish_date(
+                start, duration, task.TaskTime.DurationType, self.get_calendar(task), date_type="FINISH"
             )
             if potential_finish > finish:
                 start_ifc = ifcopenshell.util.date.datetime2ifc(start, "IfcDateTime")
@@ -116,11 +139,8 @@ class Usecase:
                     return
                 task.TaskTime.ScheduleFinish = finish_ifc
                 task.TaskTime.ScheduleStart = ifcopenshell.util.date.datetime2ifc(
-                    ifcopenshell.util.sequence.get_finish_date(
-                        finish,
-                        -duration,
-                        task.TaskTime.DurationType,
-                        self.get_calendar(task),
+                    ifcopenshell.util.sequence.get_start_or_finish_date(
+                        finish, duration, task.TaskTime.DurationType, self.get_calendar(task), date_type="START"
                     ),
                     "IfcDateTime",
                 )
@@ -131,11 +151,8 @@ class Usecase:
                 return
             task.TaskTime.ScheduleFinish = finish_ifc
             task.TaskTime.ScheduleStart = ifcopenshell.util.date.datetime2ifc(
-                ifcopenshell.util.sequence.get_finish_date(
-                    finish,
-                    -duration,
-                    task.TaskTime.DurationType,
-                    self.get_calendar(task),
+                ifcopenshell.util.sequence.get_start_or_finish_date(
+                    finish, duration, task.TaskTime.DurationType, self.get_calendar(task), date_type="START"
                 ),
                 "IfcDateTime",
             )
@@ -146,11 +163,8 @@ class Usecase:
                 return
             task.TaskTime.ScheduleStart = start_ifc
             task.TaskTime.ScheduleFinish = ifcopenshell.util.date.datetime2ifc(
-                ifcopenshell.util.sequence.get_finish_date(
-                    start,
-                    duration,
-                    task.TaskTime.DurationType,
-                    self.get_calendar(task),
+                ifcopenshell.util.sequence.get_start_or_finish_date(
+                    start, duration, task.TaskTime.DurationType, self.get_calendar(task), date_type="FINISH"
                 ),
                 "IfcDateTime",
             )
@@ -167,10 +181,7 @@ class Usecase:
         return self.calendar_cache[task.id()]
 
     def offset_date(self, date, days, duration_type, calendar):
-        return datetime.datetime.combine(
-            ifcopenshell.util.sequence.get_finish_date(date, datetime.timedelta(days=days), duration_type, calendar),
-            datetime.datetime.min.time(),
-        )
+        return ifcopenshell.util.sequence.offset_date(date, datetime.timedelta(days=days), duration_type, calendar)
 
     def get_task_time_attribute(self, task, attribute):
         if task.TaskTime:
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_task_time.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_task_time.py
index 6aa19feadf..ff0511e03a 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_task_time.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/edit_task_time.py
@@ -40,13 +40,21 @@ class Usecase:
             del self.settings["attributes"]["ScheduleFinish"]
 
         duration_type = self.settings["attributes"].get("DurationType", self.settings["task_time"].DurationType)
-        if self.settings["attributes"].get("ScheduleFinish", None):
-            self.settings["attributes"]["ScheduleFinish"] = ifcopenshell.util.sequence.get_soonest_working_day(
-                self.settings["attributes"]["ScheduleFinish"], duration_type, self.calendar
+        finish = self.settings["attributes"].get("ScheduleFinish", None)
+        if finish:
+            if isinstance(finish, str):
+                finish = datetime.datetime.fromisoformat(finish)
+            self.settings["attributes"]["ScheduleFinish"] = datetime.datetime.combine(
+                ifcopenshell.util.sequence.get_soonest_working_day(finish, duration_type, self.calendar),
+                datetime.time(17),
             )
-        if self.settings["attributes"].get("ScheduleStart", None):
-            self.settings["attributes"]["ScheduleStart"] = ifcopenshell.util.sequence.get_soonest_working_day(
-                self.settings["attributes"]["ScheduleStart"], duration_type, self.calendar
+        start = self.settings["attributes"].get("ScheduleStart", None)
+        if start:
+            if isinstance(start, str):
+                start = datetime.datetime.fromisoformat(start)
+            self.settings["attributes"]["ScheduleStart"] = datetime.datetime.combine(
+                ifcopenshell.util.sequence.get_soonest_working_day(start, duration_type, self.calendar),
+                datetime.time(9),
             )
 
         for name, value in self.settings["attributes"].items():
@@ -76,20 +84,21 @@ class Usecase:
             ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=self.task)
 
     def calculate_finish(self):
-        finish_date = ifcopenshell.util.sequence.get_finish_date(
+        finish = ifcopenshell.util.sequence.get_start_or_finish_date(
             ifcopenshell.util.date.ifc2datetime(self.settings["task_time"].ScheduleStart),
             ifcopenshell.util.date.ifc2datetime(self.settings["task_time"].ScheduleDuration),
             self.settings["task_time"].DurationType,
             self.calendar,
+            date_type="FINISH",
         )
-        self.settings["task_time"].ScheduleFinish = ifcopenshell.util.date.datetime2ifc(finish_date, "IfcDateTime")
+        self.settings["task_time"].ScheduleFinish = ifcopenshell.util.date.datetime2ifc(finish, "IfcDateTime")
 
     def calculate_duration(self):
         start = ifcopenshell.util.date.ifc2datetime(self.settings["task_time"].ScheduleStart)
         finish = ifcopenshell.util.date.ifc2datetime(self.settings["task_time"].ScheduleFinish)
         current_date = datetime.date(start.year, start.month, start.day)
         finish_date = datetime.date(finish.year, finish.month, finish.day)
-        duration = datetime.timedelta()
+        duration = datetime.timedelta(days=1)
         while current_date < finish_date:
             if self.settings["task_time"].DurationType == "ELAPSEDTIME" or not self.calendar:
                 duration += datetime.timedelta(days=1)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/recalculate_schedule.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/recalculate_schedule.py
index a55196944f..93082a39f8 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/recalculate_schedule.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/recalculate_schedule.py
@@ -36,6 +36,9 @@ class Usecase:
         self.start_dates = []
         self.build_network_graph()
 
+        if not self.start_dates:
+            return
+
         self.pending_nodes = set(self.g.nodes)
         while self.pending_nodes:
             remaining_nodes = set()
@@ -113,24 +116,25 @@ class Usecase:
         predecessor_types = [rel.SequenceType for rel in task.IsSuccessorFrom]
         successor_types = [rel.SequenceType for rel in task.IsPredecessorTo]
 
-        if not predecessor_types or (
-            "FINISH_START" not in predecessor_types and "START_START" not in predecessor_types
-        ):
+        if not predecessor_types:
             self.edges.append(("start", task.id(), {"lag_time": 0, "type": "FS"}))
             if task.TaskTime and task.TaskTime.ScheduleStart:
                 self.start_dates.append(ifcopenshell.util.date.ifc2datetime(task.TaskTime.ScheduleStart))
-        if not successor_types or ("FINISH_START" not in successor_types and "FINISH_FINISH" not in successor_types):
-            self.edges.append((task.id(), "finish", {"lag_time": 0, "type": "FS"}))
+        if not successor_types:
+            self.edges.append((task.id(), "finish", {"lag_time": 0, "type": "FF"}))
 
     def update_task_times(self):
         for ifc_definition_id in self.g.nodes:
+            if ifc_definition_id in ("start", "finish"):
+                continue
             data = self.g.nodes[ifc_definition_id]
-            if not data["duration"]:
+            task = self.file.by_id(ifc_definition_id)
+            if not task.TaskTime:
                 continue
             ifcopenshell.api.run(
                 "sequence.edit_task_time",
                 self.file,
-                task_time=self.file.by_id(ifc_definition_id).TaskTime,
+                task_time=task.TaskTime,
                 attributes={
                     "FreeFloat": ifcopenshell.util.date.datetime2ifc(data["free_float"], "IfcDuration"),
                     "TotalFloat": ifcopenshell.util.date.datetime2ifc(data["total_float"], "IfcDuration"),
@@ -143,7 +147,7 @@ class Usecase:
             )
 
     def offset_date(self, date, days, node):
-        return ifcopenshell.util.sequence.get_finish_date(
+        return ifcopenshell.util.sequence.offset_date(
             date, datetime.timedelta(days=days), node["duration_type"], node["calendar"]
         )
 
@@ -164,45 +168,74 @@ class Usecase:
                     finish = predecessor_data.get("early_finish")
                     if finish is None:
                         return
-                    if not edge["lag_time"]:
-                        starts.append(finish)
+                    days = 0 if predecessor_data["duration"] == 0 else 1
+                    if edge["lag_time"]:
+                        days += edge["lag_time"]
+                    if days:
+                        starts.append(datetime.datetime.combine(self.offset_date(finish, days, data), datetime.time(9)))
+                        starts.append(
+                            datetime.datetime.combine(
+                                self.offset_date(finish, days, predecessor_data), datetime.time(9)
+                            )
+                        )
                     else:
-                        starts.append(self.offset_date(finish, edge["lag_time"], data))
-                        starts.append(self.offset_date(finish, edge["lag_time"], predecessor_data))
+                        starts.append(finish)
                 elif edge["type"] == "SS":
                     start = predecessor_data.get("early_start")
                     if start is None:
                         return
-                    if not edge["lag_time"]:
-                        starts.append(start)
-                    else:
+                    if edge["lag_time"]:
                         starts.append(self.offset_date(start, edge["lag_time"], data))
                         starts.append(self.offset_date(start, edge["lag_time"], predecessor_data))
+                    else:
+                        starts.append(start)
                 elif edge["type"] == "FF":
                     finish = predecessor_data.get("early_finish")
                     if finish is None:
                         return
-                    if not edge["lag_time"]:
-                        finishes.append(finish)
-                    else:
+                    if edge["lag_time"]:
                         finishes.append(self.offset_date(finish, edge["lag_time"], data))
                         finishes.append(self.offset_date(finish, edge["lag_time"], predecessor_data))
+                    else:
+                        finishes.append(finish)
                 elif edge["type"] == "SF":
                     start = predecessor_data.get("early_start")
                     if start is None:
                         return
-                    if not edge["lag_time"]:
-                        finishes.append(start)
+                    days = -1
+                    if edge["lag_time"]:
+                        days += edge["lag_time"]
+                    if days or edge["lag_time"]:
+                        finishes.append(
+                            datetime.datetime.combine(self.offset_date(start, days, data), datetime.time(17))
+                        )
+                        finishes.append(
+                            datetime.datetime.combine(
+                                self.offset_date(start, days, predecessor_data), datetime.time(17)
+                            )
+                        )
                     else:
-                        finishes.append(self.offset_date(start, edge["lag_time"], data))
-                        finishes.append(self.offset_date(start, edge["lag_time"], predecessor_data))
+                        finishes.append(start)
             if starts and finishes:
                 data["early_start"] = max(starts)
                 data["early_finish"] = max(finishes)
-                if self.offset_date(data["early_start"], data["duration"], data) > data["early_finish"]:
-                    data["early_finish"] = self.offset_date(data["early_start"], data["duration"], data)
+                potential_finish = ifcopenshell.util.sequence.get_start_or_finish_date(
+                    data["early_start"],
+                    datetime.timedelta(days=data["duration"]),
+                    data["duration_type"],
+                    data["calendar"],
+                    date_type="FINISH",
+                )
+                if potential_finish > data["early_finish"]:
+                    data["early_finish"] = potential_finish
                 else:
-                    data["early_start"] = self.offset_date(data["early_finish"], -data["duration"], data)
+                    data["early_start"] = ifcopenshell.util.sequence.get_start_or_finish_date(
+                        data["early_finish"],
+                        datetime.timedelta(days=data["duration"]),
+                        data["duration_type"],
+                        data["calendar"],
+                        date_type="START",
+                    )
             elif finishes:
                 data["early_finish"] = max(finishes)
             elif starts:
@@ -211,9 +244,21 @@ class Usecase:
                 print("How did this happen?")
 
         if data.get("early_finish") is None:
-            data["early_finish"] = self.offset_date(data["early_start"], data["duration"], data)
+            data["early_finish"] = ifcopenshell.util.sequence.get_start_or_finish_date(
+                data["early_start"],
+                datetime.timedelta(days=data["duration"]),
+                data["duration_type"],
+                data["calendar"],
+                date_type="FINISH",
+            )
         elif data.get("early_start") is None:
-            data["early_start"] = self.offset_date(data["early_finish"], -data["duration"], data)
+            data["early_start"] = ifcopenshell.util.sequence.get_start_or_finish_date(
+                data["early_finish"],
+                datetime.timedelta(days=data["duration"]),
+                data["duration_type"],
+                data["calendar"],
+                date_type="START",
+            )
 
         return True
 
@@ -235,25 +280,36 @@ class Usecase:
                     start = successor_data.get("late_start")
                     if start is None:
                         return
-                    if not edge["lag_time"]:
-                        finishes.append(start)
+                    days = 1
+                    if edge["lag_time"]:
+                        days += edge["lag_time"]
+                    if days or edge["lag_time"]:
+                        finishes.append(
+                            datetime.datetime.combine(self.offset_date(start, -days, data), datetime.time(17))
+                        )
+                        finishes.append(
+                            datetime.datetime.combine(self.offset_date(start, -days, successor_data), datetime.time(17))
+                        )
                     else:
-                        finishes.append(self.offset_date(start, -edge["lag_time"], data))
-                        finishes.append(self.offset_date(start, -edge["lag_time"], successor_data))
+                        finishes.append(start)
                     free_floats.append(
                         self.calculate_free_float(
-                            data["early_finish"], successor_data["early_start"], edge["lag_time"], data, successor_data
+                            data["early_finish"].date() + datetime.timedelta(days=1),
+                            successor_data["early_start"].date(),
+                            edge["lag_time"],
+                            data,
+                            successor_data,
                         )
                     )
                 elif edge["type"] == "SS":
                     start = successor_data.get("late_start")
                     if start is None:
                         return
-                    if not edge["lag_time"]:
-                        starts.append(start)
-                    else:
+                    if edge["lag_time"]:
                         starts.append(self.offset_date(start, -edge["lag_time"], data))
                         starts.append(self.offset_date(start, -edge["lag_time"], successor_data))
+                    else:
+                        starts.append(start)
                     free_floats.append(
                         self.calculate_free_float(
                             data["early_start"], successor_data["early_start"], edge["lag_time"], data, successor_data
@@ -263,11 +319,11 @@ class Usecase:
                     finish = successor_data.get("late_finish")
                     if finish is None:
                         return
-                    if not edge["lag_time"]:
-                        finishes.append(finish)
-                    else:
+                    if edge["lag_time"]:
                         finishes.append(self.offset_date(finish, -edge["lag_time"], data))
                         finishes.append(self.offset_date(finish, -edge["lag_time"], successor_data))
+                    else:
+                        finishes.append(finish)
                     free_floats.append(
                         self.calculate_free_float(
                             data["early_finish"], successor_data["early_finish"], edge["lag_time"], data, successor_data
@@ -277,11 +333,18 @@ class Usecase:
                     finish = successor_data.get("late_finish")
                     if finish is None:
                         return
-                    if not edge["lag_time"]:
-                        starts.append(finish)
+                    days = 0 if successor_data["duration"] == 0 else -1
+                    if edge["lag_time"]:
+                        days += edge["lag_time"]
+                    if days:
+                        starts.append(
+                            datetime.datetime.combine(self.offset_date(finish, -days, data), datetime.time(9))
+                        )
+                        starts.append(
+                            datetime.datetime.combine(self.offset_date(finish, -days, successor_data), datetime.time(9))
+                        )
                     else:
-                        starts.append(self.offset_date(finish, -edge["lag_time"], data))
-                        starts.append(self.offset_date(finish, -edge["lag_time"], successor_data))
+                        starts.append(finish)
                     free_floats.append(
                         self.calculate_free_float(
                             data["early_start"], successor_data["early_finish"], edge["lag_time"], data, successor_data
@@ -291,9 +354,21 @@ class Usecase:
                 data["late_start"] = min(starts)
                 data["late_finish"] = min(finishes)
                 if self.offset_date(data["late_start"], data["duration"], data) < data["late_finish"]:
-                    data["late_finish"] = self.offset_date(data["late_start"], data["duration"], data)
+                    data["late_finish"] = ifcopenshell.util.sequence.get_start_or_finish_date(
+                        data["late_start"],
+                        datetime.timedelta(days=data["duration"]),
+                        data["duration_type"],
+                        data["calendar"],
+                        date_type="FINISH",
+                    )
                 else:
-                    data["late_start"] = self.offset_date(data["late_finish"], -data["duration"], data)
+                    data["late_start"] = ifcopenshell.util.sequence.get_start_or_finish_date(
+                        data["late_finish"],
+                        datetime.timedelta(days=data["duration"]),
+                        data["duration_type"],
+                        data["calendar"],
+                        date_type="START",
+                    )
             elif finishes:
                 data["late_finish"] = min(finishes)
             elif starts:
@@ -302,9 +377,21 @@ class Usecase:
                 print("How did this happen?")
 
         if data.get("late_finish") is None:
-            data["late_finish"] = self.offset_date(data["late_start"], data["duration"], data)
+            data["late_finish"] = ifcopenshell.util.sequence.get_start_or_finish_date(
+                data["late_start"],
+                datetime.timedelta(days=data["duration"]),
+                data["duration_type"],
+                data["calendar"],
+                date_type="FINISH",
+            )
         elif data.get("late_start") is None:
-            data["late_start"] = self.offset_date(data["late_finish"], -data["duration"], data)
+            data["late_start"] = ifcopenshell.util.sequence.get_start_or_finish_date(
+                data["late_finish"],
+                datetime.timedelta(days=data["duration"]),
+                data["duration_type"],
+                data["calendar"],
+                date_type="START",
+            )
 
         if data["duration_type"] == "WORKTIME":
             data["total_float"] = datetime.timedelta(
@@ -314,8 +401,14 @@ class Usecase:
             )
         else:
             data["total_float"] = data["late_finish"] - data["early_finish"]
+            # If the float is within the span of a single day, it may show as a 8 hours
+            if data["total_float"].seconds == 60 * 60 * 8:
+                data["total_float"] = datetime.timedelta(days=data["total_float"].days + 1)
 
         data["free_float"] = min(free_floats) if free_floats else None
+        # If the float is within the span of a single day, it may show as a 8 hours
+        if data["free_float"] and data["free_float"].seconds == 60 * 60 * 8:
+            data["free_float"] = datetime.timedelta(days=data["free_float"].days + 1)
 
         return True
 
diff --git a/src/ifcopenshell-python/ifcopenshell/api/sequence/remove_task.py b/src/ifcopenshell-python/ifcopenshell/api/sequence/remove_task.py
index edd271731d..6783b5ade5 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/sequence/remove_task.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/sequence/remove_task.py
@@ -44,5 +44,10 @@ class Usecase:
                 elif inverse.RelatedObjects == tuple(self.settings["task"]):
                     self.file.remove(inverse)
             elif inverse.is_a("IfcRelAssignsToControl"):
-                self.file.remove(inverse)
+                if len(inverse.RelatedObjects) == 1:
+                    self.file.remove(inverse)
+                else:
+                    related_objects = list(inverse.RelatedObjects)
+                    related_objects.remove(self.settings["task"])
+                    inverse.RelatedObjects = related_objects
         self.file.remove(self.settings["task"])
diff --git a/src/ifcopenshell-python/ifcopenshell/requirements.txt b/src/ifcopenshell-python/ifcopenshell/requirements.txt
index 232aae9415..d0a2328f34 100644
--- a/src/ifcopenshell-python/ifcopenshell/requirements.txt
+++ b/src/ifcopenshell-python/ifcopenshell/requirements.txt
@@ -1,4 +1,4 @@
-lxml==4.6.3
-numpy==1.20.3
+lxml==4.6.5
+numpy==1.21.0
 regex==2021.4.4
 xmlschema==1.6.4
\ No newline at end of file
diff --git a/src/ifcopenshell-python/ifcopenshell/util/element.py b/src/ifcopenshell-python/ifcopenshell/util/element.py
index 0f7b1b1c66..caa618d373 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/element.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/element.py
@@ -133,6 +133,29 @@ def get_material(element, should_skip_usage=False):
         return get_material(relating_type, should_skip_usage)
 
 
+def get_elements_by_material(ifc_file, material):
+    results = []
+    for inverse in ifc_file.get_inverse(material):
+        if inverse.is_a("IfcRelAssociatesMaterial"):
+            results.extend(inverse.RelatedObjects)
+        elif inverse.is_a("IfcMaterialLayer"):
+            for material_set in inverse.ToMaterialLayerSet:
+                results.extend(get_elements_by_material(ifc_file, material_set))
+        elif inverse.is_a("IfcMaterialProfile"):
+            for material_set in inverse.ToMaterialProfileSet:
+                results.extend(get_elements_by_material(ifc_file, material_set))
+        elif inverse.is_a("IfcMaterialConstituent"):
+            for material_set in inverse.ToMaterialConstituentSet:
+                results.extend(get_elements_by_material(ifc_file, material_set))
+        elif inverse.is_a("IfcMaterialLayerSetUsage"):
+            results.extend(get_elements_by_material(ifc_file, inverse))
+        elif inverse.is_a("IfcMaterialProfileSetUsage"):
+            results.extend(get_elements_by_material(ifc_file, inverse))
+        elif inverse.is_a("IfcMaterialList"):
+            results.extend(get_elements_by_material(ifc_file, inverse))
+    return results
+
+
 def get_layers(ifc_file, element):
     layers = []
     representations = []
diff --git a/src/ifcopenshell-python/ifcopenshell/util/entity_to_type_map_4.json b/src/ifcopenshell-python/ifcopenshell/util/entity_to_type_map_4.json
index 8756097053..b719ad79b4 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/entity_to_type_map_4.json
+++ b/src/ifcopenshell-python/ifcopenshell/util/entity_to_type_map_4.json
@@ -90,7 +90,8 @@
         "IfcDistributionChamberElementType"
     ],
     "IfcDoor": [
-        "IfcDoorType"
+        "IfcDoorType",
+        "IfcDoorStyle"
     ],
     "IfcDuctFitting": [
         "IfcDuctFittingType"
@@ -306,7 +307,8 @@
         "IfcWasteTerminalType"
     ],
     "IfcWindow": [
-        "IfcWindowType"
+        "IfcWindowType",
+        "IfcWindowStyle"
     ],
     "IfcBeamStandardCase": [
         "IfcBeamType"
diff --git a/src/ifcopenshell-python/ifcopenshell/util/selector.py b/src/ifcopenshell-python/ifcopenshell/util/selector.py
index 326a36de56..910f287647 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/selector.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/selector.py
@@ -23,8 +23,10 @@ import lark
 
 
 class Selector:
-    def parse(self, ifc_file, query):
-        self.file = ifc_file
+    @classmethod
+    def parse(cls, ifc_file, query, elements=None):
+        cls.file = ifc_file
+        cls.elements = elements
 
         l = lark.Lark(
             """start: query (lfunction query)*
@@ -35,22 +37,26 @@ class Selector:
                     class_selector: "." WORD filter ?
                     filter: "[" filter_key (comparison filter_value)? "]"
                     filter_key: WORD | pset_or_qto
-                    filter_value: ESCAPED_STRING
+                    filter_value: ESCAPED_STRING | SIGNED_FLOAT | SIGNED_INT | BOOLEAN | NULL
                     pset_or_qto: /[A-Za-z0-9_]+/ "." /[A-Za-z0-9_]+/
                     lfunction: and | or
-                    inverse_relationship: types | contains_elements | boundedby
+                    inverse_relationship: types | decomposed_by | bounded_by
                     types: "*"
-                    contains_elements: "@"
-                    boundedby: "@@"
+                    decomposed_by: "@"
+                    bounded_by: "@@"
                     and: "&"
                     or: "|"
-                    comparison: contains | morethanequalto | lessthanequalto | equal | morethan | lessthan
+                    not: "!"
+                    comparison: (not)* (oneof | contains | morethanequalto | lessthanequalto | equal | morethan | lessthan)
+                    oneof: "%="
                     contains: "*="
                     morethanequalto: ">="
-                    lessthanequalto: "<"
+                    lessthanequalto: "<="
                     equal: "="
                     morethan: ">"
                     lessthan: "<"
+                    BOOLEAN: "TRUE" | "FALSE" | "true" | "false"| "True" | "False"
+                    NULL: "NULL"
 
                     // Embed common.lark for packaging
                     DIGIT: "0".."9"
@@ -82,13 +88,14 @@ class Selector:
         )
 
         start = l.parse(query)
-        return self.get_group(start)
+        return cls.get_group(start)
 
-    def get_group(self, group):
+    @classmethod
+    def get_group(cls, group):
         lfunction = None
         for child in group.children:
             if child.data == "query":
-                new_results = self.get_query(child)
+                new_results = cls.get_query(child)
                 if not lfunction:
                     results = new_results
                 elif lfunction == "or":
@@ -100,14 +107,16 @@ class Selector:
                 lfunction = child.children[0].data
         return results
 
-    def get_query(self, query):
+    @classmethod
+    def get_query(cls, query):
         for child in query.children:
             if child.data == "selector":
-                return self.get_selector(child)
+                return cls.get_selector(child)
             elif child.data == "group":
-                return self.get_group(child)
+                return cls.get_group(child)
 
-    def get_selector(self, selector):
+    @classmethod
+    def get_selector(cls, selector):
         if len(selector.children) == 1:
             inverse_relationship = None
             class_or_guid_selector = selector.children[0]
@@ -116,15 +125,16 @@ class Selector:
             class_or_guid_selector = selector.children[1]
 
         if class_or_guid_selector.data == "class_selector":
-            results = self.get_class_selector(class_or_guid_selector)
+            results = cls.get_class_selector(class_or_guid_selector)
         elif class_or_guid_selector.data == "guid_selector":
-            results = self.get_guid_selector(class_or_guid_selector)
+            results = cls.get_guid_selector(class_or_guid_selector)
 
         if not inverse_relationship:
             return results
-        return self.parse_inverse_relationship(results, inverse_relationship.children[0].data)
+        return cls.parse_inverse_relationship(results, inverse_relationship.children[0].data)
 
-    def parse_inverse_relationship(self, elements, inverse_relationship):
+    @classmethod
+    def parse_inverse_relationship(cls, elements, inverse_relationship):
         results = []
         for element in elements:
             if inverse_relationship == "types":
@@ -132,28 +142,32 @@ class Selector:
                     results.extend(element.Types[0].RelatedObjects)
                 elif hasattr(element, "ObjectTypeOf") and element.ObjectTypeOf:
                     results.extend(element.ObjectTypeOf[0].RelatedObjects)
-            elif inverse_relationship == "contains_elements" and hasattr(element, "ContainsElements"):
-                for relationship in element.ContainsElements:
-                    results.extend(relationship.RelatedElements)
-            elif inverse_relationship == "boundedby" and hasattr(element, "BoundedBy"):
+            elif inverse_relationship == "decomposed_by":
+                results.extend(ifcopenshell.util.element.get_decomposition(element))
+            elif inverse_relationship == "bounded_by" and hasattr(element, "BoundedBy"):
                 for relationship in element.BoundedBy:
                     results.append(relationship.RelatedBuildingElement)
         return results
 
-    def get_class_selector(self, class_selector):
+    @classmethod
+    def get_class_selector(cls, class_selector):
         if class_selector.children[0] == "COBie":
-            elements = ifcopenshell.util.fm.get_cobie_components(self.file)
+            elements = ifcopenshell.util.fm.get_cobie_components(cls.file)
         elif class_selector.children[0] == "COBieType":
-            elements = ifcopenshell.util.fm.get_cobie_types(self.file)
+            elements = ifcopenshell.util.fm.get_cobie_types(cls.file)
         elif class_selector.children[0] == "FMHEM":
-            elements = ifcopenshell.util.fm.get_fmhem_types(self.file)
+            elements = ifcopenshell.util.fm.get_fmhem_types(cls.file)
         else:
-            elements = self.file.by_type(class_selector.children[0])
+            if cls.elements is None:
+                elements = cls.file.by_type(class_selector.children[0])
+            else:
+                elements = [e for e in cls.elements if e.is_a(class_selector.children[0])]
         if len(class_selector.children) > 1 and class_selector.children[1].data == "filter":
-            return self.filter_elements(elements, class_selector.children[1])
+            return cls.filter_elements(elements, class_selector.children[1])
         return elements
 
-    def filter_elements(self, elements, filter_rule):
+    @classmethod
+    def filter_elements(cls, elements, filter_rule):
         results = []
         key = filter_rule.children[0].children[0]
         if not isinstance(key, str):
@@ -161,16 +175,29 @@ class Selector:
         comparison = value = None
         if len(filter_rule.children) > 1:
             comparison = filter_rule.children[1].children[0].data
-            value = filter_rule.children[2].children[0][1:-1]
+            if comparison == "not":
+                comparison += filter_rule.children[1].children[1].data
+            token_type = filter_rule.children[2].children[0].type
+            if token_type == "ESCAPED_STRING":
+                value = str(filter_rule.children[2].children[0][1:-1])
+            elif token_type == "SIGNED_INT":
+                value = int(filter_rule.children[2].children[0])
+            elif token_type == "SIGNED_FLOAT":
+                value = float(filter_rule.children[2].children[0])
+            elif token_type == "BOOLEAN":
+                value = filter_rule.children[2].children[0].lower() == 'true'
+            elif token_type == "NULL":
+                value = None
         for element in elements:
-            element_value = self.get_element_value(element, key)
-            if element_value is None:
+            element_value = cls.get_element_value(element, key)
+            if element_value is None and value is not None:
                 continue
-            if not comparison or self.filter_element(element, element_value, comparison, value):
+            if not comparison or cls.filter_element(element, element_value, comparison, value):
                 results.append(element)
         return results
 
-    def get_element_value(self, element, key):
+    @classmethod
+    def get_element_value(cls, element, key):
         if "." in key and key.split(".")[0] == "type":
             try:
                 element = ifcopenshell.util.element.get_type(element)
@@ -206,20 +233,26 @@ class Selector:
             if pset_name in psets and prop in psets[pset_name]:
                 return psets[pset_name][prop]
 
-    def filter_element(self, element, element_value, comparison, value):
-        if comparison == "equal":
-            return str(element_value) == value
+    @classmethod
+    def filter_element(cls, element, element_value, comparison, value):
+        if comparison.startswith("not"):
+            return not cls.filter_element(element, element_value, comparison[3:], value)
+        elif comparison == "equal":
+            return element_value == value
         elif comparison == "contains":
             return value in str(element_value)
         elif comparison == "morethan":
-            return element_value > float(value)
+            return element_value > value
         elif comparison == "lessthan":
-            return element_value < float(value)
+            return element_value < value
         elif comparison == "morethanequalto":
-            return element_value >= float(value)
+            return element_value >= value
         elif comparison == "lessthanequalto":
-            return element_value <= float(value)
+            return element_value <= value
+        elif comparison == "oneof":
+            return element_value in value.split(",")
         return False
 
-    def get_guid_selector(self, guid_selector):
-        return [self.file.by_id(guid_selector.children[0])]
+    @classmethod
+    def get_guid_selector(cls, guid_selector):
+        return [cls.file.by_id(guid_selector.children[0])]
diff --git a/src/ifcopenshell-python/ifcopenshell/util/sequence.py b/src/ifcopenshell-python/ifcopenshell/util/sequence.py
index e9235faeb8..ab020f5ab4 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/sequence.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/sequence.py
@@ -40,12 +40,28 @@ def count_working_days(start, finish, calendar):
     while current_date < finish_date:
         if calendar and calendar.WorkingTimes and is_working_day(current_date, calendar):
             result += 1
+        elif not calendar:
+            result += 1
         current_date += datetime.timedelta(days=1)
     return result
 
 
-def get_finish_date(start, duration, duration_type, calendar):
-    current_date = datetime.date(start.year, start.month, start.day)
+def get_start_or_finish_date(start, duration, duration_type, calendar, date_type="FINISH"):
+    if not duration.days:
+        # Typically a milestone will have zero duration, so the start == finish
+        return start
+    # We minus 1 because the start day itself is counted as a day
+    duration = datetime.timedelta(days=duration.days - 1)
+    if date_type == "START":
+        duration = -duration
+    result = offset_date(start, duration, duration_type, calendar)
+    if date_type == "START":
+        return datetime.datetime.combine(result, datetime.time(9))
+    return datetime.datetime.combine(result, datetime.time(17))
+
+
+def offset_date(start, duration, duration_type, calendar):
+    current_date = start
     abs_duration = abs(duration.days)
     date_offset = datetime.timedelta(days=1 if duration.days > 0 else -1)
     while abs_duration > 0:
diff --git a/src/ifcopenshell-python/test/api/document/test_add_information.py b/src/ifcopenshell-python/test/api/document/test_add_information.py
new file mode 100644
index 0000000000..4d225e1f39
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/document/test_add_information.py
@@ -0,0 +1,47 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestAddInformation(test.bootstrap.IFC4):
+    def test_adding_information(self):
+        project = self.file.createIfcProject()
+        element = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        assert element.is_a("IfcDocumentInformation")
+        assert len(self.file.by_type("IfcDocumentInformation")) == 1
+
+    def test_adding_information_to_the_project(self):
+        project = self.file.createIfcProject()
+        element = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        rel = element.DocumentInfoForObjects[0]
+        assert rel.is_a("IfcRelAssociatesDocument")
+        assert rel.RelatedObjects[0] == project
+
+    def test_adding_a_subdocument(self):
+        project = self.file.createIfcProject()
+        parent = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        element = ifcopenshell.api.run("document.add_information", self.file, parent=parent)
+        assert element.is_a("IfcDocumentInformation")
+        assert len(self.file.by_type("IfcDocumentInformation")) == 2
+        assert element.IsPointedTo[0].RelatingDocument == parent
+        assert parent.IsPointer[0].RelatedDocuments[0] == element
+        element2 = ifcopenshell.api.run("document.add_information", self.file, parent=parent)
+        assert element in parent.IsPointer[0].RelatedDocuments
+        assert element2 in parent.IsPointer[0].RelatedDocuments
diff --git a/src/ifcopenshell-python/test/api/document/test_add_reference_.py b/src/ifcopenshell-python/test/api/document/test_add_reference_.py
new file mode 100644
index 0000000000..584bbf44a6
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/document/test_add_reference_.py
@@ -0,0 +1,35 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestAddReference(test.bootstrap.IFC4):
+    def test_adding_a_reference(self):
+        element = ifcopenshell.api.run("document.add_reference", self.file, information=None)
+        assert element.is_a("IfcDocumentReference")
+        assert len(self.file.by_type("IfcDocumentReference")) == 1
+
+    def test_adding_a_reference_to_an_information(self):
+        self.file.createIfcProject()
+        information = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        element = ifcopenshell.api.run("document.add_reference", self.file, information=information)
+        assert element.is_a("IfcDocumentReference")
+        assert len(self.file.by_type("IfcDocumentReference")) == 1
+        assert element.ReferencedDocument == information
diff --git a/src/ifcopenshell-python/test/api/document/test_remove_information.py b/src/ifcopenshell-python/test/api/document/test_remove_information.py
new file mode 100644
index 0000000000..4df4857052
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/document/test_remove_information.py
@@ -0,0 +1,50 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestRemoveInformation(test.bootstrap.IFC4):
+    def test_remove_information(self):
+        project = self.file.createIfcProject()
+        element = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        ifcopenshell.api.run("document.remove_information", self.file, information=element)
+        assert len(self.file.by_type("IfcDocumentInformation")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesDocument")) == 0
+
+    def test_removing_all_references_of_an_information(self):
+        project = self.file.createIfcProject()
+        information = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        ifcopenshell.api.run("document.add_reference", self.file, information=information)
+        ifcopenshell.api.run("document.remove_information", self.file, information=information)
+        assert len(self.file.by_type("IfcDocumentInformation")) == 0
+        assert len(self.file.by_type("IfcDocumentReference")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesDocument")) == 0
+
+    def test_removing_all_subdocuments_and_their_references_too(self):
+        project = self.file.createIfcProject()
+        information = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        information2 = ifcopenshell.api.run("document.add_information", self.file, parent=information)
+        ifcopenshell.api.run("document.add_reference", self.file, information=information)
+        ifcopenshell.api.run("document.add_reference", self.file, information=information2)
+        ifcopenshell.api.run("document.remove_information", self.file, information=information)
+        assert len(self.file.by_type("IfcDocumentInformation")) == 0
+        assert len(self.file.by_type("IfcDocumentReference")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesDocument")) == 0
+        assert len(self.file.by_type("IfcDocumentInformationRelationship")) == 0
diff --git a/src/ifcopenshell-python/test/api/document/test_remove_reference_.py b/src/ifcopenshell-python/test/api/document/test_remove_reference_.py
new file mode 100644
index 0000000000..e5f5892172
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/document/test_remove_reference_.py
@@ -0,0 +1,43 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestRemoveReference(test.bootstrap.IFC4):
+    def test_removing_reference(self):
+        project = self.file.createIfcProject()
+        information = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        reference = ifcopenshell.api.run("document.add_reference", self.file, information=information)
+        ifcopenshell.api.run("document.remove_reference", self.file, reference=reference)
+        assert len(self.file.by_type("IfcDocumentReference")) == 0
+        assert len(self.file.by_type("IfcDocumentInformation")) == 1
+        assert len(self.file.by_type("IfcRelAssociatesDocument")) == 1
+
+    def test_removing_a_reference_assigned_to_an_object(self):
+        project = self.file.createIfcProject()
+        wall = self.file.createIfcWall()
+        information = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        reference = ifcopenshell.api.run("document.add_reference", self.file, information=information)
+        ifcopenshell.api.run("document.assign_document", self.file, product=wall, document=reference)
+        assert len(self.file.by_type("IfcRelAssociatesDocument")) == 2
+        ifcopenshell.api.run("document.remove_reference", self.file, reference=reference)
+        assert len(self.file.by_type("IfcDocumentReference")) == 0
+        assert len(self.file.by_type("IfcDocumentInformation")) == 1
+        assert len(self.file.by_type("IfcRelAssociatesDocument")) == 1
diff --git a/src/ifcopenshell-python/test/api/material/test_add_material_set.py b/src/ifcopenshell-python/test/api/material/test_add_material_set.py
new file mode 100644
index 0000000000..7adb706f08
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/material/test_add_material_set.py
@@ -0,0 +1,41 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestAddMaterialSet(test.bootstrap.IFC4):
+    def test_add_layer_set(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        assert material.LayerSetName == "Unnamed"
+        assert material.is_a("IfcMaterialLayerSet")
+
+    def test_add_profile_set(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialProfileSet")
+        assert material.Name == "Unnamed"
+        assert material.is_a("IfcMaterialProfileSet")
+
+    def test_add_constituent_set(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialConstituentSet")
+        assert material.Name == "Unnamed"
+        assert material.is_a("IfcMaterialConstituentSet")
+
+    def test_add_list(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialList")
+        assert material.is_a("IfcMaterialList")
diff --git a/src/ifcopenshell-python/test/api/material/test_remove_material.py b/src/ifcopenshell-python/test/api/material/test_remove_material.py
new file mode 100644
index 0000000000..80e0abb1f3
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/material/test_remove_material.py
@@ -0,0 +1,117 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestRemoveMaterial(test.bootstrap.IFC4):
+    def test_removing_material(self):
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterial")) == 0
+
+    def test_removing_material_with_associations(self):
+        wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material)
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterial")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
+
+    def test_removing_material_in_layer(self):
+        wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run(
+            "material.add_material_set", self.file, set_type="IfcMaterialLayerSet"
+        )
+        ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material_set)
+        assert len(self.file.by_type("IfcMaterialLayerSet")[0].MaterialLayers) == 1
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterial")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
+        assert len(self.file.by_type("IfcMaterialLayerSet")[0].MaterialLayers) == 0
+
+    def test_removing_material_in_profile(self):
+        wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run(
+            "material.add_material_set", self.file, set_type="IfcMaterialProfileSet"
+        )
+        ifcopenshell.api.run("material.add_profile", self.file, profile_set=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material_set)
+        assert len(self.file.by_type("IfcMaterialProfileSet")[0].MaterialProfiles) == 1
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterial")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
+        assert len(self.file.by_type("IfcMaterialProfileSet")[0].MaterialProfiles) == 0
+
+    def test_removing_material_in_constituent(self):
+        wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run(
+            "material.add_material_set", self.file, set_type="IfcMaterialConstituentSet"
+        )
+        ifcopenshell.api.run("material.add_constituent", self.file, constituent_set=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material_set)
+        assert len(self.file.by_type("IfcMaterialConstituentSet")[0].MaterialConstituents) == 1
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterial")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
+        assert self.file.by_type("IfcMaterialConstituentSet")[0].MaterialConstituents is None
+
+    def test_removing_material_in_list(self):
+        wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run(
+            "material.add_material_set", self.file, set_type="IfcMaterialList"
+        )
+        ifcopenshell.api.run("material.add_list_item", self.file, material_list=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material_set)
+        assert len(self.file.by_type("IfcMaterialList")[0].Materials) == 1
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterial")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
+        assert len(self.file.by_type("IfcMaterialList")[0].Materials) == 0
+
+    def test_removing_a_material_with_a_style_definition(self):
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcProject")
+        context = ifcopenshell.api.run("context.add_context", self.file, context_type="Model")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        style = ifcopenshell.api.run("style.add_style", self.file)
+        ifcopenshell.api.run("style.assign_material_style", self.file, material=material, style=style, context=context)
+        assert len(self.file.by_type("IfcMaterialDefinitionRepresentation")) == 1
+        assert len(self.file.by_type("IfcStyledRepresentation")) == 1
+        assert len(self.file.by_type("IfcStyledItem")) == 1
+        assert len(self.file.by_type("IfcSurfaceStyle")) == 1
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterial")) == 0
+        assert len(self.file.by_type("IfcMaterialDefinitionRepresentation")) == 0
+        assert len(self.file.by_type("IfcStyledRepresentation")) == 0
+        assert len(self.file.by_type("IfcStyledItem")) == 0
+        assert len(self.file.by_type("IfcSurfaceStyle")) == 1
+
+    def test_removing_a_material_with_properties(self):
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=material, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": "Bar"})
+        assert material.HasProperties
+        ifcopenshell.api.run("material.remove_material", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterialProperties")) == 0
+        assert len(self.file.by_type("IfcPropertySingleValue")) == 0
diff --git a/src/ifcopenshell-python/test/api/material/test_remove_material_set.py b/src/ifcopenshell-python/test/api/material/test_remove_material_set.py
new file mode 100644
index 0000000000..fe78ce351c
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/material/test_remove_material_set.py
@@ -0,0 +1,53 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestRemoveMaterialSet(test.bootstrap.IFC4):
+    def test_removing_material_set(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterialLayerSet")) == 0
+
+    def test_removing_material_set_with_associations(self):
+        wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material)
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterialLayerSet")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
+
+    def test_removing_a_material_set_with_set_items_but_preserving_materials(self):
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material_set)
+        assert len(self.file.by_type("IfcMaterialLayerSet")) == 0
+        assert len(self.file.by_type("IfcMaterialLayer")) == 0
+        assert len(self.file.by_type("IfcMaterial")) == 1
+
+    def test_removing_a_material_set_with_properties(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=material, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": "Bar"})
+        assert material.HasProperties
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterialProperties")) == 0
+        assert len(self.file.by_type("IfcPropertySingleValue")) == 0
diff --git a/src/ifcopenshell-python/test/api/pset/test_remove_pset.py b/src/ifcopenshell-python/test/api/pset/test_remove_pset.py
new file mode 100644
index 0000000000..4f5291a3ef
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/pset/test_remove_pset.py
@@ -0,0 +1,59 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestRemovePset(test.bootstrap.IFC4):
+    def test_removing_pset(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        assert len(self.file.by_type("IfcRelDefinesByProperties")) == 1
+        ifcopenshell.api.run("pset.remove_pset", self.file, product=element, pset=pset)
+        assert len(self.file.by_type("IfcRelDefinesByProperties")) == 0
+        assert len(self.file.by_type("IfcPropertySet")) == 0
+
+    def test_only_unassigning_if_pset_is_used_by_other_elements(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        rel = self.file.by_type("IfcRelDefinesByProperties")[0]
+        rel.RelatedObjects = [element, element2]
+        assert len(self.file.by_type("IfcRelDefinesByProperties")) == 1
+        ifcopenshell.api.run("pset.remove_pset", self.file, product=element, pset=pset)
+        assert ifcopenshell.util.element.get_psets(element) == {}
+        assert "Foo_Bar" in ifcopenshell.util.element.get_psets(element2)
+
+    def test_removing_a_pset_with_properties(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": "Bar"})
+        ifcopenshell.api.run("pset.remove_pset", self.file, product=element, pset=pset)
+        assert len(self.file.by_type("IfcRelDefinesByProperties")) == 0
+        assert len(self.file.by_type("IfcPropertySet")) == 0
+        assert len(self.file.by_type("IfcPropertySingleValue")) == 0
+
+    def test_removing_a_qto_with_quantities(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        qto = ifcopenshell.api.run("pset.add_qto", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_qto", self.file, qto=qto, properties={"Foo": 42})
+        ifcopenshell.api.run("pset.remove_pset", self.file, product=element, pset=qto)
+        assert len(self.file.by_type("IfcRelDefinesByProperties")) == 0
+        assert len(self.file.by_type("IfcQuantitySet")) == 0
+        assert len(self.file.by_type("IfcPhysicalSimpleQuantity")) == 0
diff --git a/src/ifcopenshell-python/test/api/sequence/test_cascade_schedule.py b/src/ifcopenshell-python/test/api/sequence/test_cascade_schedule.py
index c3811b3758..48e101559b 100644
--- a/src/ifcopenshell-python/test/api/sequence/test_cascade_schedule.py
+++ b/src/ifcopenshell-python/test/api/sequence/test_cascade_schedule.py
@@ -32,10 +32,10 @@ class TestCascadeSchedule(test.bootstrap.IFC4):
         task2 = self._create_task("P1D")
 
         ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
-        assert task.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task2.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
 
     def test_only_cascading_to_successors_not_predecessors(self):
         task = self._create_task("P1D")
@@ -45,13 +45,13 @@ class TestCascadeSchedule(test.bootstrap.IFC4):
         self._create_sequence(task, task3, "FINISH_START", lag="P1D")
 
         ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task2)
-        assert task.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleStart == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleFinish == "2000-01-04T00:00:00"
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-03T17:00:00"
         # We assert that these start finish times have not cascaded
-        assert task3.TaskTime.ScheduleStart == "2000-01-02T00:00:00"
-        assert task3.TaskTime.ScheduleFinish == "2000-01-05T00:00:00"
+        assert task3.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-04T17:00:00"
 
     def test_cascading_finish_to_start(self):
         task = self._create_task("P1D")
@@ -61,12 +61,27 @@ class TestCascadeSchedule(test.bootstrap.IFC4):
         self._create_sequence(task, task3, "FINISH_START", lag="P1D")
 
         ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
-        assert task.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleStart == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleFinish == "2000-01-04T00:00:00"
-        assert task3.TaskTime.ScheduleStart == "2000-01-03T00:00:00"
-        assert task3.TaskTime.ScheduleFinish == "2000-01-06T00:00:00"
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-03T17:00:00"
+        assert task3.TaskTime.ScheduleStart == "2000-01-03T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-05T17:00:00"
+
+    def test_cascading_finish_to_start_for_milestones(self):
+        task = self._create_task("P0D")
+        task2 = self._create_task("P2D")
+        task3 = self._create_task("P3D")
+        self._create_sequence(task, task2, "FINISH_START")
+        self._create_sequence(task, task3, "FINISH_START", lag="P1D")
+
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T09:00:00"
+        assert task2.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-02T17:00:00"
+        assert task3.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-04T17:00:00"
 
     def test_cascading_finish_to_finish(self):
         task = self._create_task("P1D")
@@ -76,12 +91,12 @@ class TestCascadeSchedule(test.bootstrap.IFC4):
         self._create_sequence(task, task3, "FINISH_FINISH", lag="P1D")
 
         ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
-        assert task.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleStart == "1999-12-31T00:00:00"
-        assert task2.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
-        assert task3.TaskTime.ScheduleStart == "1999-12-31T00:00:00"
-        assert task3.TaskTime.ScheduleFinish == "2000-01-03T00:00:00"
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.ScheduleStart == "1999-12-31T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task3.TaskTime.ScheduleStart == "1999-12-31T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-02T17:00:00"
 
     def test_cascading_start_to_start(self):
         task = self._create_task("P1D")
@@ -91,12 +106,12 @@ class TestCascadeSchedule(test.bootstrap.IFC4):
         self._create_sequence(task, task3, "START_START", lag="P1D")
 
         ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
-        assert task.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task2.TaskTime.ScheduleFinish == "2000-01-03T00:00:00"
-        assert task3.TaskTime.ScheduleStart == "2000-01-02T00:00:00"
-        assert task3.TaskTime.ScheduleFinish == "2000-01-05T00:00:00"
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-02T17:00:00"
+        assert task3.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-04T17:00:00"
 
     def test_cascading_start_to_finish(self):
         task = self._create_task("P1D")
@@ -106,15 +121,32 @@ class TestCascadeSchedule(test.bootstrap.IFC4):
         self._create_sequence(task, task3, "START_FINISH", lag="P1D")
 
         ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
-        assert task.TaskTime.ScheduleStart == "2000-01-01T00:00:00"
-        assert task.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
-        assert task2.TaskTime.ScheduleStart == "1999-12-30T00:00:00"
-        assert task2.TaskTime.ScheduleFinish == "2000-01-01T00:00:00"
-        assert task3.TaskTime.ScheduleStart == "1999-12-30T00:00:00"
-        assert task3.TaskTime.ScheduleFinish == "2000-01-02T00:00:00"
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.ScheduleStart == "1999-12-30T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "1999-12-31T17:00:00"
+        assert task3.TaskTime.ScheduleStart == "1999-12-30T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+
+    def test_cascading_start_to_finish_for_milestones(self):
+        task = self._create_task("P0D")
+        task2 = self._create_task("P2D")
+        task3 = self._create_task("P3D")
+        self._create_sequence(task, task2, "START_FINISH")
+        self._create_sequence(task, task3, "START_FINISH", lag="P1D")
+
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T09:00:00"
+        assert task2.TaskTime.ScheduleStart == "1999-12-30T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "1999-12-31T17:00:00"
+        assert task3.TaskTime.ScheduleStart == "1999-12-30T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
 
     def _create_task(self, duration):
         task = ifcopenshell.api.run("sequence.add_task", self.file)
+        if duration == "P0D":
+            task.IsMilestone = True
         task_time = ifcopenshell.api.run("sequence.add_task_time", self.file, task=task)
         ifcopenshell.api.run(
             "sequence.edit_task_time",
diff --git a/src/ifcopenshell-python/test/api/sequence/test_edit_task_time.py b/src/ifcopenshell-python/test/api/sequence/test_edit_task_time.py
index 4055b0194d..552bbce520 100644
--- a/src/ifcopenshell-python/test/api/sequence/test_edit_task_time.py
+++ b/src/ifcopenshell-python/test/api/sequence/test_edit_task_time.py
@@ -34,19 +34,19 @@ class TestEditTaskTime(test.bootstrap.IFC4):
                 "UserDefinedDataOrigin": "UserDefinedDataOrigin",
                 "DurationType": "ELAPSEDTIME",
                 "ScheduleDuration": "P1D",
-                "ScheduleStart": "2000-01-01T00:00:00",
-                "ScheduleFinish": "2000-01-02T00:00:00",
+                "ScheduleStart": "2000-01-01T09:00:00",
+                "ScheduleFinish": "2000-01-01T17:00:00",
                 "EarlyStart": "2000-01-01T00:00:00",
-                "EarlyFinish": "2000-01-02T00:00:00",
+                "EarlyFinish": "2000-01-01T00:00:00",
                 "LateStart": "2000-01-01T00:00:00",
-                "LateFinish": "2000-01-02T00:00:00",
+                "LateFinish": "2000-01-01T00:00:00",
                 "FreeFloat": "P0D",
                 "TotalFloat": "P0D",
                 "IsCritical": True,
                 "StatusTime": "2000-01-01T00:00:00",
                 "ActualDuration": "P1D",
-                "ActualStart": "2000-01-01T00:00:00",
-                "ActualFinish": "2000-01-02T00:00:00",
+                "ActualStart": "2000-01-01T09:00:00",
+                "ActualFinish": "2000-01-01T17:00:00",
                 "RemainingTime": "P1D",
                 "Completion": 0.5,
             },
@@ -56,19 +56,19 @@ class TestEditTaskTime(test.bootstrap.IFC4):
         assert task_time.UserDefinedDataOrigin == "UserDefinedDataOrigin"
         assert task_time.DurationType == "ELAPSEDTIME"
         assert task_time.ScheduleDuration == "P1D"
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
-        assert task_time.ScheduleFinish == "2000-01-02T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
+        assert task_time.ScheduleFinish == "2000-01-01T17:00:00"
         assert task_time.EarlyStart == "2000-01-01T00:00:00"
-        assert task_time.EarlyFinish == "2000-01-02T00:00:00"
+        assert task_time.EarlyFinish == "2000-01-01T00:00:00"
         assert task_time.LateStart == "2000-01-01T00:00:00"
-        assert task_time.LateFinish == "2000-01-02T00:00:00"
+        assert task_time.LateFinish == "2000-01-01T00:00:00"
         assert task_time.FreeFloat == "P0D"
         assert task_time.TotalFloat == "P0D"
         assert task_time.IsCritical == True
         assert task_time.StatusTime == "2000-01-01T00:00:00"
         assert task_time.ActualDuration == "P1D"
-        assert task_time.ActualStart == "2000-01-01T00:00:00"
-        assert task_time.ActualFinish == "2000-01-02T00:00:00"
+        assert task_time.ActualStart == "2000-01-01T09:00:00"
+        assert task_time.ActualFinish == "2000-01-01T17:00:00"
         assert task_time.RemainingTime == "P1D"
         assert task_time.Completion == 0.5
 
@@ -80,11 +80,11 @@ class TestEditTaskTime(test.bootstrap.IFC4):
             task_time=task_time,
             attributes={
                 "ScheduleDuration": None,
-                "ScheduleStart": "2000-01-01T00:00:00",
+                "ScheduleStart": "2000-01-01T09:00:00",
                 "ScheduleFinish": None,
             },
         )
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
         assert task_time.ScheduleFinish is None
         assert task_time.ScheduleDuration is None
 
@@ -104,7 +104,7 @@ class TestEditTaskTime(test.bootstrap.IFC4):
                 "ScheduleFinish": None,
             },
         )
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
         assert task_time.ScheduleFinish is None
         assert task_time.ScheduleDuration is None
 
@@ -117,13 +117,13 @@ class TestEditTaskTime(test.bootstrap.IFC4):
             attributes={
                 "DurationType": "ELAPSEDTIME",
                 "ScheduleDuration": "P1D",
-                "ScheduleStart": "2000-01-01T00:00:00",
+                "ScheduleStart": "2000-01-01T09:00:00",
             },
         )
         assert task_time.DurationType == "ELAPSEDTIME"
         assert task_time.ScheduleDuration == "P1D"
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
-        assert task_time.ScheduleFinish == "2000-01-02T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
+        assert task_time.ScheduleFinish == "2000-01-01T17:00:00"
 
     def test_schedule_durations_are_auto_calculated_if_possible(self):
         task_time = ifcopenshell.api.run("sequence.add_task_time", self.file, task=self.file.createIfcTask())
@@ -133,14 +133,14 @@ class TestEditTaskTime(test.bootstrap.IFC4):
             task_time=task_time,
             attributes={
                 "DurationType": "ELAPSEDTIME",
-                "ScheduleStart": "2000-01-01T00:00:00",
-                "ScheduleFinish": "2000-01-02T00:00:00",
+                "ScheduleStart": "2000-01-01T09:00:00",
+                "ScheduleFinish": "2000-01-01T17:00:00",
             },
         )
         assert task_time.DurationType == "ELAPSEDTIME"
         assert task_time.ScheduleDuration == "P1D"
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
-        assert task_time.ScheduleFinish == "2000-01-02T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
+        assert task_time.ScheduleFinish == "2000-01-01T17:00:00"
 
     def test_a_duration_takes_priority_over_start_and_finish_dates(self):
         task_time = ifcopenshell.api.run("sequence.add_task_time", self.file, task=self.file.createIfcTask())
@@ -151,14 +151,14 @@ class TestEditTaskTime(test.bootstrap.IFC4):
             attributes={
                 "DurationType": "ELAPSEDTIME",
                 "ScheduleDuration": "P1D",
-                "ScheduleStart": "2000-01-01T00:00:00",
-                "ScheduleFinish": "2000-01-03T00:00:00",
+                "ScheduleStart": "2000-01-01T09:00:00",
+                "ScheduleFinish": "2000-01-03T17:00:00",
             },
         )
         assert task_time.DurationType == "ELAPSEDTIME"
         assert task_time.ScheduleDuration == "P1D"
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
-        assert task_time.ScheduleFinish == "2000-01-02T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
+        assert task_time.ScheduleFinish == "2000-01-01T17:00:00"
 
     def test_durations_can_be_specified_in_datetime_objects(self):
         task_time = ifcopenshell.api.run("sequence.add_task_time", self.file, task=self.file.createIfcTask())
@@ -169,13 +169,13 @@ class TestEditTaskTime(test.bootstrap.IFC4):
             attributes={
                 "DurationType": "ELAPSEDTIME",
                 "ScheduleDuration": datetime.timedelta(days=1),
-                "ScheduleStart": "2000-01-01T00:00:00",
+                "ScheduleStart": "2000-01-01T09:00:00",
             },
         )
         assert task_time.DurationType == "ELAPSEDTIME"
         assert task_time.ScheduleDuration == "P1D"
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
-        assert task_time.ScheduleFinish == "2000-01-02T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
+        assert task_time.ScheduleFinish == "2000-01-01T17:00:00"
 
     def test_zero_durations_are_allowed(self):
         task_time = ifcopenshell.api.run("sequence.add_task_time", self.file, task=self.file.createIfcTask())
@@ -186,10 +186,10 @@ class TestEditTaskTime(test.bootstrap.IFC4):
             attributes={
                 "DurationType": "ELAPSEDTIME",
                 "ScheduleDuration": datetime.timedelta(),
-                "ScheduleStart": "2000-01-01T00:00:00",
+                "ScheduleStart": "2000-01-01T09:00:00",
             },
         )
         assert task_time.DurationType == "ELAPSEDTIME"
         assert task_time.ScheduleDuration == "P0D"
-        assert task_time.ScheduleStart == "2000-01-01T00:00:00"
-        assert task_time.ScheduleFinish == "2000-01-01T00:00:00"
+        assert task_time.ScheduleStart == "2000-01-01T09:00:00"
+        assert task_time.ScheduleFinish == "2000-01-01T09:00:00"
diff --git a/src/ifcopenshell-python/test/api/sequence/test_recalculate_schedule.py b/src/ifcopenshell-python/test/api/sequence/test_recalculate_schedule.py
new file mode 100644
index 0000000000..399bd132cc
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/sequence/test_recalculate_schedule.py
@@ -0,0 +1,284 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import datetime
+import test.bootstrap
+import ifcopenshell.api
+
+
+# A good way for checking these is to recreate them in ProjectLibre
+class TestRecalculateSchedule(test.bootstrap.IFC4):
+    def test_doing_nothing_if_the_task_has_no_time(self):
+        self._add_work_schedule()
+        task = ifcopenshell.api.run("sequence.add_task", self.file)
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime is None
+
+    def test_recalculating_for_a_single_task(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+
+    def test_recalculating_finish_to_start(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        self._create_sequence(task, task2, "FINISH_START")
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+        assert task2.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.EarlyStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.EarlyFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.LateStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.LateFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.TotalFloat == "P0D"
+        assert task2.TaskTime.FreeFloat == "P0D"
+        assert task2.TaskTime.IsCritical is True
+
+    def test_recalculating_multiple_finish_to_start(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        task3 = self._create_task("P3D")
+        self._create_sequence(task, task2, "FINISH_START")
+        self._create_sequence(task, task3, "FINISH_START", lag="P1D")
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+        assert task2.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.EarlyStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.EarlyFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.LateStart == "2000-01-04T09:00:00"
+        assert task2.TaskTime.LateFinish == "2000-01-05T17:00:00"
+        assert task2.TaskTime.TotalFloat == "P2D"
+        assert task2.TaskTime.FreeFloat == "P2D"
+        assert task2.TaskTime.IsCritical is False
+        assert task3.TaskTime.ScheduleStart == "2000-01-03T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-05T17:00:00"
+        assert task3.TaskTime.EarlyStart == "2000-01-03T09:00:00"
+        assert task3.TaskTime.EarlyFinish == "2000-01-05T17:00:00"
+        assert task3.TaskTime.LateStart == "2000-01-03T09:00:00"
+        assert task3.TaskTime.LateFinish == "2000-01-05T17:00:00"
+        assert task3.TaskTime.TotalFloat == "P0D"
+        assert task3.TaskTime.FreeFloat == "P0D"
+        assert task3.TaskTime.IsCritical is True
+
+    def test_recalculating_finish_to_start_with_a_milestone(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        task3 = self._create_task("P0D")
+        self._create_sequence(task, task2, "FINISH_START")
+        self._create_sequence(task, task3, "FINISH_START", lag="P1D")
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+        assert task2.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.EarlyStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.EarlyFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.LateStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.LateFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.TotalFloat == "P0D"
+        assert task2.TaskTime.FreeFloat == "P0D"
+        assert task2.TaskTime.IsCritical is True
+        assert task3.TaskTime.ScheduleStart == "2000-01-03T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-03T09:00:00"
+        assert task3.TaskTime.EarlyStart == "2000-01-03T09:00:00"
+        assert task3.TaskTime.EarlyFinish == "2000-01-03T09:00:00"
+        assert task3.TaskTime.LateStart == "2000-01-03T17:00:00"
+        assert task3.TaskTime.LateFinish == "2000-01-03T17:00:00"
+        assert task3.TaskTime.TotalFloat == "P1D"
+        assert task3.TaskTime.FreeFloat == "P1D"
+        assert task3.TaskTime.IsCritical is False
+
+    def test_recalculating_finish_to_start_with_a_milestone_as_the_last_task(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        task3 = self._create_task("P0D")
+        self._create_sequence(task, task2, "FINISH_START")
+        self._create_sequence(task2, task3, "FINISH_START")
+        ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+        assert task2.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.EarlyStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.EarlyFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.LateStart == "2000-01-02T09:00:00"
+        assert task2.TaskTime.LateFinish == "2000-01-03T17:00:00"
+        assert task2.TaskTime.TotalFloat == "P0D"
+        assert task2.TaskTime.FreeFloat == "P0D"
+        assert task2.TaskTime.IsCritical is True
+        assert task3.TaskTime.ScheduleStart == "2000-01-04T09:00:00"
+        assert task3.TaskTime.ScheduleFinish == "2000-01-04T09:00:00"
+        assert task3.TaskTime.EarlyStart == "2000-01-04T09:00:00"
+        assert task3.TaskTime.EarlyFinish == "2000-01-04T09:00:00"
+        assert task3.TaskTime.LateStart == "2000-01-04T09:00:00"
+        assert task3.TaskTime.LateFinish == "2000-01-04T09:00:00"
+        assert task3.TaskTime.TotalFloat == "P0D"
+        assert task3.TaskTime.FreeFloat == "P0D"
+        assert task3.TaskTime.IsCritical is True
+
+    def test_recalculating_finish_to_finish(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        self._create_sequence(task, task2, "FINISH_FINISH")
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+        assert task2.TaskTime.ScheduleStart == "1999-12-31T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.EarlyStart == "1999-12-31T09:00:00"
+        assert task2.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.LateStart == "1999-12-31T09:00:00"
+        assert task2.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task2.TaskTime.TotalFloat == "P0D"
+        assert task2.TaskTime.FreeFloat == "P0D"
+        assert task2.TaskTime.IsCritical is True
+
+    def test_recalculating_start_to_start(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        self._create_sequence(task, task2, "START_START")
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+        assert task2.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "2000-01-02T17:00:00"
+        assert task2.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task2.TaskTime.EarlyFinish == "2000-01-02T17:00:00"
+        assert task2.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task2.TaskTime.LateFinish == "2000-01-02T17:00:00"
+        assert task2.TaskTime.TotalFloat == "P0D"
+        assert task2.TaskTime.FreeFloat == "P0D"
+        assert task2.TaskTime.IsCritical is True
+
+    def test_recalculating_start_to_finish(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        self._create_sequence(task, task2, "START_FINISH")
+        ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+        assert task.TaskTime.ScheduleStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.ScheduleFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.EarlyStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.EarlyFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.LateStart == "2000-01-01T09:00:00"
+        assert task.TaskTime.LateFinish == "2000-01-01T17:00:00"
+        assert task.TaskTime.TotalFloat == "P0D"
+        assert task.TaskTime.FreeFloat == "P0D"
+        assert task.TaskTime.IsCritical is True
+        assert task2.TaskTime.ScheduleStart == "1999-12-30T09:00:00"
+        assert task2.TaskTime.ScheduleFinish == "1999-12-31T17:00:00"
+        assert task2.TaskTime.EarlyStart == "1999-12-30T09:00:00"
+        assert task2.TaskTime.EarlyFinish == "1999-12-31T17:00:00"
+        assert task2.TaskTime.LateStart == "1999-12-30T09:00:00"
+        assert task2.TaskTime.LateFinish == "1999-12-31T17:00:00"
+        assert task2.TaskTime.TotalFloat == "P0D"
+        assert task2.TaskTime.FreeFloat == "P0D"
+        assert task2.TaskTime.IsCritical is True
+
+    def _add_work_schedule(self):
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcProject")
+        self.work_schedule = ifcopenshell.api.run("sequence.add_work_schedule", self.file)
+
+    def _create_task(self, duration):
+        task = ifcopenshell.api.run("sequence.add_task", self.file, work_schedule=self.work_schedule)
+        if duration == "P0D":
+            task.IsMilestone = True
+        task_time = ifcopenshell.api.run("sequence.add_task_time", self.file, task=task)
+        ifcopenshell.api.run(
+            "sequence.edit_task_time",
+            self.file,
+            task_time=task_time,
+            attributes={"ScheduleStart": datetime.date(2000, 1, 1), "ScheduleDuration": duration},
+        )
+        return task
+
+    def _create_sequence(self, predecessor, successor, relationship, lag=None):
+        rel = ifcopenshell.api.run(
+            "sequence.assign_sequence", self.file, relating_process=predecessor, related_process=successor
+        )
+        ifcopenshell.api.run(
+            "sequence.edit_sequence", self.file, rel_sequence=rel, attributes={"SequenceType": relationship}
+        )
+        if lag:
+            ifcopenshell.api.run(
+                "sequence.assign_lag_time", self.file, rel_sequence=rel, lag_value=lag, duration_type="WORKTIME"
+            )
diff --git a/src/ifcopenshell-python/test/bootstrap.py b/src/ifcopenshell-python/test/bootstrap.py
index a5b6905f31..b87d30855b 100644
--- a/src/ifcopenshell-python/test/bootstrap.py
+++ b/src/ifcopenshell-python/test/bootstrap.py
@@ -28,6 +28,8 @@ class IFC4:
         self.file = ifcopenshell.api.run("project.create_file")
         ifcopenshell.api.owner.settings.get_user = lambda ifc: (ifc.by_type("IfcPersonAndOrganization") or [None])[0]
         ifcopenshell.api.owner.settings.get_application = lambda ifc: (ifc.by_type("IfcApplication") or [None])[0]
+        ifcopenshell.api.pre_listeners = {}
+        ifcopenshell.api.post_listeners = {}
 
 
 class IFC2X3:
@@ -36,3 +38,5 @@ class IFC2X3:
         self.file = ifcopenshell.api.run("project.create_file", version="IFC2X3")
         ifcopenshell.api.owner.settings.get_user = lambda ifc: ifc.createIfcPersonAndOrganization()
         ifcopenshell.api.owner.settings.get_application = lambda ifc: ifc.createIfcApplication()
+        ifcopenshell.api.pre_listeners = {}
+        ifcopenshell.api.post_listeners = {}
diff --git a/src/ifcopenshell-python/test/util/test_element.py b/src/ifcopenshell-python/test/util/test_element.py
index 3ad1ecc4cd..8a14e6993f 100644
--- a/src/ifcopenshell-python/test/util/test_element.py
+++ b/src/ifcopenshell-python/test/util/test_element.py
@@ -268,6 +268,60 @@ class TestGetMaterial(test.bootstrap.IFC4):
         assert subject.get_material(element) == material
 
 
+class TestGetElementsByMaterial(test.bootstrap.IFC4):
+    def test_getting_elements_of_a_material(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        assert subject.get_elements_by_material(self.file, material) == [element]
+
+    def test_getting_elements_of_a_material_layer_set(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        ifcopenshell.api.run("type.assign_type", self.file, related_object=element, relating_type=element_type)
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage")
+        usage = self.file.by_type("IfcMaterialLayerSetUsage")[0]
+        assert set(subject.get_elements_by_material(self.file, material)) == {element, element_type}
+        assert set(subject.get_elements_by_material(self.file, material_set)) == {element, element_type}
+        assert set(subject.get_elements_by_material(self.file, usage)) == {element}
+
+    def test_getting_elements_of_a_material_profile_set(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        ifcopenshell.api.run("type.assign_type", self.file, related_object=element, relating_type=element_type)
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialProfileSet")
+        ifcopenshell.api.run("material.add_profile", self.file, profile_set=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSetUsage")
+        usage = self.file.by_type("IfcMaterialProfileSetUsage")[0]
+        assert set(subject.get_elements_by_material(self.file, material)) == {element, element_type}
+        assert set(subject.get_elements_by_material(self.file, material_set)) == {element, element_type}
+        assert set(subject.get_elements_by_material(self.file, usage)) == {element}
+
+    def test_getting_elements_of_a_material_constituent_set(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialConstituentSet")
+        ifcopenshell.api.run("material.add_constituent", self.file, constituent_set=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        assert set(subject.get_elements_by_material(self.file, material)) == {element}
+        assert set(subject.get_elements_by_material(self.file, material_set)) == {element}
+
+    def test_getting_elements_of_a_material_list(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialList")
+        ifcopenshell.api.run("material.add_list_item", self.file, material_list=material_set, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        assert set(subject.get_elements_by_material(self.file, material)) == {element}
+        assert set(subject.get_elements_by_material(self.file, material_set)) == {element}
+
+
 class TestGetlayers(test.bootstrap.IFC4):
     def test_getting_the_layer_of_a_product_representation(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
diff --git a/src/ifcopenshell-python/test/util/test_selector.py b/src/ifcopenshell-python/test/util/test_selector.py
new file mode 100644
index 0000000000..3c138098cc
--- /dev/null
+++ b/src/ifcopenshell-python/test/util/test_selector.py
@@ -0,0 +1,131 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import pytest
+import test.bootstrap
+import ifcopenshell.api
+import ifcopenshell.util.selector as subject
+
+
+class TestSelector(test.bootstrap.IFC4):
+    def test_selecting_by_class(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSlab")
+        assert subject.Selector.parse(self.file, ".IfcWall") == [element]
+
+    def test_selecting_by_globalid(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSlab")
+        assert subject.Selector.parse(self.file, f"#{element.GlobalId}") == [element]
+
+    def test_selecting_by_attribute(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element.Name = "Foobar"
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSlab")
+        assert subject.Selector.parse(self.file, '.IfcElement[Name="Foobar"]') == [element]
+        assert subject.Selector.parse(self.file, '.IfcElement[Name="Foobaz"]') == []
+
+    def test_selecting_by_string_property(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": "Bar"})
+        assert subject.Selector.parse(self.file, '.IfcElement[Foo_Bar.Foo="Bar"]') == [element]
+
+    def test_selecting_by_integer_property(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": 42})
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo=42]") == [element]
+
+    def test_selecting_by_float_property(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": 4.2})
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo=4.2]") == [element]
+
+    def test_selecting_by_boolean_property(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": True})
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo=TRUE]") == [element]
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": False})
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo=FALSE]") == [element]
+
+    def test_selecting_by_null_property(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": "Bar"})
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo=NULL]") == []
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": None})
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo=NULL]") == [element]
+
+    def test_comparing_by_not_equal(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element.Name = "Foobar"
+        assert subject.Selector.parse(self.file, '.IfcElement[Name!="Foobaz"]') == [element]
+        assert subject.Selector.parse(self.file, '.IfcElement[Name!="Foobar"]') == []
+
+    def test_comparing_by_ranges(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=element, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": 4.2})
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo>2]") == [element]
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo>20]") == []
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo<2]") == []
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo<20]") == [element]
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo>=4.2]") == [element]
+        assert subject.Selector.parse(self.file, ".IfcElement[Foo_Bar.Foo<=4.2]") == [element]
+
+    def test_comparing_if_value_contains_a_wildcard_string(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element.Name = "Foobar"
+        assert subject.Selector.parse(self.file, '.IfcElement[Name*="Foo"]') == [element]
+        assert subject.Selector.parse(self.file, '.IfcElement[Name*="oba"]') == [element]
+        assert subject.Selector.parse(self.file, '.IfcElement[Name*="abc"]') == []
+
+    def test_comparing_if_value_is_in_a_list(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element.Name = "Foobar"
+        assert subject.Selector.parse(self.file, '.IfcElement[Name%="Foobar,Foobaz"]') == [element]
+        element.Name = "Foobaz"
+        assert subject.Selector.parse(self.file, '.IfcElement[Name%="Foobar,Foobaz"]') == [element]
+        element.Name = "Foobat"
+        assert subject.Selector.parse(self.file, '.IfcElement[Name%="Foobar,Foobaz"]') == []
+
+    def test_getting_occurrences_of_a_filtered_type(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        ifcopenshell.api.run("type.assign_type", self.file, related_object=element, relating_type=element_type)
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element_type2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        ifcopenshell.api.run("type.assign_type", self.file, related_object=element2, relating_type=element_type2)
+        assert set(subject.Selector.parse(self.file, "* .IfcWallType")) == {element, element2}
+
+    def test_getting_decomposition_of_a_filtered_type(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcMember")
+        building = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        ifcopenshell.api.run("spatial.assign_container", self.file, product=element, relating_structure=building)
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
+        assert set(subject.Selector.parse(self.file, "@ .IfcBuilding")) == {element, subelement}
+
+    def test_selecting_elements_from_a_prefiltered_list(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSlab")
+        assert subject.Selector.parse(self.file, ".IfcWall", elements=[element])
+        assert not subject.Selector.parse(self.file, ".IfcWall", elements=[element2])
diff --git a/src/ifcparse/IfcParse.cpp b/src/ifcparse/IfcParse.cpp
index aa655c1945..51d344033b 100644
--- a/src/ifcparse/IfcParse.cpp
+++ b/src/ifcparse/IfcParse.cpp
@@ -168,6 +168,7 @@ IfcSpfStream::IfcSpfStream(const std::string& fn)
 		eof = len == 0;
 		ptr = 0;
 		fclose(stream);
+		stream = nullptr;
 #ifdef USE_MMAP	
 	}
 #endif
@@ -212,6 +213,9 @@ void IfcSpfStream::Close() {
 	}
 #endif
 	delete[] buffer;
+	if (stream) {
+		fclose(stream);
+	}
 }
 
 //
diff --git a/src/ifcpatch/ifcpatch/recipes/OffsetObjectPlacements.py b/src/ifcpatch/ifcpatch/recipes/OffsetObjectPlacements.py
index c399a3f574..0f8afd40d6 100644
--- a/src/ifcpatch/ifcpatch/recipes/OffsetObjectPlacements.py
+++ b/src/ifcpatch/ifcpatch/recipes/OffsetObjectPlacements.py
@@ -17,6 +17,9 @@
 # along with IfcPatch.  If not, see <http://www.gnu.org/licenses/>.
 
 import math
+import numpy as np
+import ifcopenshell
+import ifcopenshell.util.placement
 
 class Patcher:
     def __init__(self, src, file, logger, args=None):
@@ -36,49 +39,17 @@ class Patcher:
                 absolute_placements.append(absolute_placement)
         absolute_placements = set(absolute_placements)
 
+        angle = float(self.args[3])
+        transformation = self.z_rotation_matrix(math.radians(angle)) if angle else np.eye(4)
+        transformation[0][3] += float(self.args[0])
+        transformation[1][3] += float(self.args[1])
+        transformation[2][3] += float(self.args[2])
+
         for placement in absolute_placements:
-            offset_location = (
-                placement.RelativePlacement.Location.Coordinates[0] + float(self.args[0]),
-                placement.RelativePlacement.Location.Coordinates[1] + float(self.args[1]),
-                placement.RelativePlacement.Location.Coordinates[2] + float(self.args[2])
+            placement.RelativePlacement = self.get_relative_placement(
+                transformation @ ifcopenshell.util.placement.get_local_placement(placement)
             )
 
-            relative_placement = self.file.createIfcAxis2Placement3D(
-                self.file.createIfcCartesianPoint(offset_location))
-
-            if placement.RelativePlacement.Axis:
-                relative_placement.Axis = placement.RelativePlacement.Axis
-            if placement.RelativePlacement.RefDirection:
-                relative_placement.RefDirection = placement.RelativePlacement.RefDirection
-
-            angle = float(self.args[3])
-            if not angle:
-                placement.RelativePlacement = relative_placement
-                continue
-
-            rotation_matrix = self.z_rotation_matrix(math.radians(angle))
-
-            if len(self.args) == 5:
-                # Move then rotate, if you want
-                relative_placement.Location.Coordinates = self.multiply_by_matrix(offset_location, rotation_matrix)
-            else:
-                # Rotate then move, like Solibri
-                pass
-
-            if placement.RelativePlacement.Axis:
-                z_axis = placement.RelativePlacement.Axis.DirectionRatios
-                relative_placement.Axis = self.file.createIfcDirection(
-                    self.multiply_by_matrix(z_axis, rotation_matrix))
-
-            if placement.RelativePlacement.RefDirection:
-                x_axis = placement.RelativePlacement.RefDirection.DirectionRatios
-            else:
-                x_axis = (1., 0., 0.)
-            relative_placement.RefDirection = self.file.createIfcDirection(
-                self.multiply_by_matrix(x_axis, rotation_matrix))
-
-            placement.RelativePlacement = relative_placement
-
     def get_absolute_placement(self, object_placement):
         if object_placement.PlacementRelTo:
             return self.get_absolute_placement(object_placement.PlacementRelTo)
@@ -86,14 +57,26 @@ class Patcher:
 
     def z_rotation_matrix(self, angle):
         return [
-            [math.cos(angle), -math.sin(angle), 0.],
-            [math.sin(angle), math.cos(angle), 0.],
-            [0., 0., 1.]
+            [math.cos(angle), -math.sin(angle), 0., 0.],
+            [math.sin(angle), math.cos(angle), 0., 0.],
+            [0., 0., 1., 0.],
+            [0., 0., 0., 1.],
         ]
 
-    def multiply_by_matrix(self, v, m):
-        return [
-            v[0]*m[0][0] + v[1]*m[0][1] + v[2]*m[0][2],
-            v[0]*m[1][0] + v[1]*m[1][1] + v[2]*m[1][2],
-            v[0]*m[2][0] + v[1]*m[2][1] + v[2]*m[2][2]
-        ]
+    def get_relative_placement(self, m):
+        x = np.array((m[0][0], m[1][0], m[2][0]))
+        z = np.array((m[0][2], m[1][2], m[2][2]))
+        o = np.array((m[0][3], m[1][3], m[2][3]))
+        object_matrix = ifcopenshell.util.placement.a2p(o, z, x)
+        return self.create_ifc_axis_2_placement_3d(
+            object_matrix[:, 3][0:3],
+            object_matrix[:, 2][0:3],
+            object_matrix[:, 0][0:3],
+        )
+
+    def create_ifc_axis_2_placement_3d(self, point, up, forward):
+        return self.file.createIfcAxis2Placement3D(
+            self.file.createIfcCartesianPoint(point.tolist()),
+            self.file.createIfcDirection(up.tolist()),
+            self.file.createIfcDirection(forward.tolist()),
+        )
diff --git a/src/ifcwrap/IfcGeomWrapper.i b/src/ifcwrap/IfcGeomWrapper.i
index 1957b038e1..dba32a5a70 100644
--- a/src/ifcwrap/IfcGeomWrapper.i
+++ b/src/ifcwrap/IfcGeomWrapper.i
@@ -300,6 +300,33 @@ struct ShapeRTTI : public boost::static_visitor<PyObject*>
 	%}
 };
 
+%extend IfcGeom::BRepElement {
+    double calc_volume_() const {
+        double v;
+        if ($self->geometry().calculate_volume(v)) {
+            return v;
+        } else {
+            return std::numeric_limits<double>::quiet_NaN();
+        }
+    }
+
+    double calc_surface_area_() const {
+        double v;
+        if ($self->geometry().calculate_surface_area(v)) {
+            return v;
+        } else {
+            return std::numeric_limits<double>::quiet_NaN();
+        }
+    }
+
+    %pythoncode %{
+        # Hide the getters with read-only property implementations
+        geometry = property(geometry)
+        volume = property(calc_volume_)
+        surface_area = property(calc_surface_area_)
+    %}    
+};
+
 %extend IfcGeom::Material {
 	%pythoncode %{
         # Hide the getters with read-only property implementations
diff --git a/src/serializers/SvgSerializer.cpp b/src/serializers/SvgSerializer.cpp
index f7f3d6b570..96738e9942 100644
--- a/src/serializers/SvgSerializer.cpp
+++ b/src/serializers/SvgSerializer.cpp
@@ -36,7 +36,6 @@
 #include <TopoDS_Edge.hxx>
 #include <TopExp_Explorer.hxx>
 #include <BRep_Tool.hxx>
-#include <BRepAlgo_Section.hxx>
 #include <BRepTools.hxx>
 #include <BRepAlgoAPI_Section.hxx>
 #include <ShapeAnalysis_FreeBounds.hxx>