Gets the pick list for bSDD properties with Allowed Values working

- assert isinstance(res, list) was wrong because duplicate_task returns a tuple not a list
- removed overkill assertion anyway as the usecase is already typed.
- setting optional name or reuse planned schedule name
- usecase now returns created baseline work schedule

src/bonsai/bonsai/tool/bsdd.py

@@ -170,7 +170,7 @@ class Bsdd(bonsai.core.tool.Bsdd):
             psets.setdefault(pset, {})
 
             predefined_value = prop.get("predefinedValue")
-            if predefined_value:
+            if predefined_value and predefined_value != "None":
                 possible_values = [predefined_value]
             else:
                 possible_values = prop.get("allowedValues", []) or []
@@ -369,7 +369,7 @@ class Bsdd(bonsai.core.tool.Bsdd):
             data = cls.bsdd_properties[bsdd_prop.uri]
 
             predefined_value = data.get("predefinedValue")
-            if predefined_value:
+            if predefined_value and predefined_value != "None":
                 possible_values = [predefined_value]
             else:
                 possible_values = data.get("allowedValues", []) or []
@@ -401,7 +401,13 @@ class Bsdd(bonsai.core.tool.Bsdd):
                 uris.add(uri)
         psets = set()
         for uri in uris:
-            if not (bsdd_class := cls.bsdd_classes.get(uri, None)):
+            try:
+                # Cache may not be populated yet (e.g. a fresh session that never
+                # browsed this class), so fetch on a cache miss instead of skipping.
+                bsdd_class = cls.get_bsdd_class(uri)
+            except Exception:
+                continue
+            if not bsdd_class:
                 continue
             for class_pset in bsdd_class.get("classProperties", []):
                 if not (pset_name := class_pset.get("propertySet", None)):
@@ -409,6 +415,37 @@ class Bsdd(bonsai.core.tool.Bsdd):
                 psets.add((uri, bsdd_class["name"], pset_name))
         return psets
 
+    @classmethod
+    def get_bsdd_pset_property_values(
+        cls, element: ifcopenshell.entity_instance, pset_name: str
+    ) -> dict[str, list[str]]:
+        """Map bSDD property code -> allowed/predefined values for properties bSDD says
+        are applicable to `element` (via its classification references) under `pset_name`.
+
+        Used to recognise a Pset property as bSDD-sourced even outside the dedicated
+        bSDD add-property flow (e.g. a Pset created in a previous session), so it can
+        still be edited as a picklist.
+        """
+        result: dict[str, list[str]] = {}
+        for uri, class_name, applicable_pset_name in cls.get_applicable_psets(element):
+            if applicable_pset_name != pset_name:
+                continue
+            bsdd_class = cls.get_bsdd_class(uri)
+            for class_prop in bsdd_class.get("classProperties", []):
+                if class_prop.get("propertySet") != pset_name:
+                    continue
+                code = class_prop.get("propertyCode")
+                if not code or code in result:
+                    continue
+                predefined_value = class_prop.get("predefinedValue")
+                if predefined_value and predefined_value != "None":
+                    result[code] = [predefined_value]
+                    continue
+                allowed_values = class_prop.get("allowedValues", []) or []
+                if allowed_values:
+                    result[code] = [v["value"] for v in allowed_values]
+        return result
+
     @classmethod
     def is_applicable(cls, pset_uri: str, element: ifcopenshell.entity_instance) -> bool:
         uris = set()

src/bonsai/bonsai/tool/pset.py

@@ -223,6 +223,18 @@ class Pset(bonsai.core.tool.Pset):
         elif pset.is_a("IfcMaterialProperties") or pset.is_a("IfcProfileProperties"):
             pset_props = pset.Properties
 
+        # If this Pset's owning element is classified against a bSDD class that defines
+        # this Pset, recognise properties matching bSDD property codes as picklists,
+        # even though the Pset wasn't necessarily created through the bSDD add-property UI.
+        bsdd_allowed_values: dict[str, list[str]] = {}
+        if pset.is_a("IfcPropertySet"):
+            elements = ifcopenshell.util.element.get_elements_by_pset(pset)
+            if elements:
+                try:
+                    bsdd_allowed_values = tool.Bsdd.get_bsdd_pset_property_values(next(iter(elements)), pset.Name)
+                except Exception:
+                    pass
+
         prop_templates: dict[str, ifcopenshell.entity_instance] = {}
         if pset_template:
             prop_templates = {prop.Name: prop for prop in pset_template.HasPropertyTemplates}
@@ -286,6 +298,17 @@ class Pset(bonsai.core.tool.Pset):
                 metadata.set_value(metadata.get_value_default() if metadata.is_null else value)
                 process_prop_description(metadata)
 
+                if prop.is_a("IfcPropertySingleValue") and (possible_values := bsdd_allowed_values.get(prop.Name)):
+                    str_value = None if value is None else str(value)
+                    if str_value is not None and str_value not in possible_values:
+                        # Preserve a legacy/imported value that doesn't match the current
+                        # bSDD enumeration instead of silently dropping it.
+                        possible_values = [*possible_values, str_value]
+                    metadata.enum_items = json.dumps(possible_values)
+                    metadata.data_type = "enum"
+                    if str_value is not None:
+                        metadata.enum_value = str_value
+
     @classmethod
     def get_prop_template_primitive_type(cls, prop_template: ifcopenshell.entity_instance) -> str:
         if prop_template.TemplateType in ["Q_LENGTH", "Q_AREA", "Q_VOLUME", "Q_WEIGHT", "Q_TIME"]:

src/bsdd/bsdd.py

@@ -1026,7 +1026,7 @@ def apply_ifc_classification_properties(
     psets = ifcopenshell.util.element.get_psets(element)
     for prop in classificationProperties:
         predefinedValue = prop.get("predefinedValue")
-        if not predefinedValue or prop.get("propertyDomainName") != "IFC":
+        if not predefinedValue or predefinedValue == "None" or prop.get("propertyDomainName") != "IFC":
             continue
         pset = psets.get(prop["propertySet"])
         if pset:

src/ifcopenshell-python/ifcopenshell/api/alignment/__init__.py

@@ -25,7 +25,7 @@ are automatically created and maintained.
 
 Alignments are created with stationing referents. Each layout segment is assigned a position referent that informs about
 the start point of the segment. An example is the point of curvature of a horizontal circular curve. The referent is
-nested to the segment representing the circular arc and is named with a indicator of the position and the station, e.g. "P.C. (145+98.32)"
+nested to the segment representing the circular arc and is named with the alignment name and an indicator of the position and the station, e.g. "MyAlignment 145+98.32 (P.C.)"
 
 This API does not determine alignment parameters based on rules, such as minimum curve radius as a function of design speed or sight distance.
 
@@ -89,6 +89,7 @@ from .layout_vertical_alignment_by_pi_method import (
     layout_vertical_alignment_by_pi_method,
 )
 from .name_segments import name_segments
+from .update_alignment_parameter_segment_tags import update_alignment_parameter_segment_tags
 from .update_end_point import update_end_point
 from .update_fallback_position import update_fallback_position
 from .update_key_point_referents import update_key_point_referents
@@ -132,6 +133,7 @@ __all__ = [
     "layout_vertical_alignment_by_pi_method",
     "name_segments",
     "register_referent_name_callback",
+    "update_alignment_parameter_segment_tags",
     "update_end_point",
     "update_fallback_position",
     "update_key_point_referents",

src/ifcopenshell-python/ifcopenshell/api/alignment/_get_key_point_tag.py

@@ -0,0 +1,30 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.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
+import ifcopenshell.util.alignment
+
+
+def _get_key_point_tag(file: ifcopenshell.file, label: str, station: float) -> str:
+    """
+    Builds the station-and-label text shared by update_alignment_parameter_segment_tags (used
+    directly as IfcAlignmentParameterSegment.StartTag/EndTag) and update_key_point_referents (used,
+    prefixed with the alignment name, as IfcReferent.Name): "<station> (<label>)", e.g.
+    "145+98.32 (P.O.B.)".
+    """
+    return f"{ifcopenshell.util.alignment.station_as_string(file, station)} ({label})"

src/ifcopenshell-python/ifcopenshell/api/alignment/update_alignment_parameter_segment_tags.py

@@ -0,0 +1,108 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.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
+import ifcopenshell.api.alignment
+from ifcopenshell import entity_instance
+from ifcopenshell.api.alignment._get_key_point_tag import _get_key_point_tag
+from ifcopenshell.api.alignment._get_segment_start_point_label import (
+    _get_segment_start_point_label,
+)
+
+
+def update_alignment_parameter_segment_tags(
+    file: ifcopenshell.file, layout: entity_instance, label_end_tag: bool = False
+) -> None:
+    """
+    Sets IfcAlignmentParameterSegment.StartTag (and, optionally, EndTag) for every segment
+    transition in an alignment layout. Unlike update_key_point_referents, this does not create any
+    IfcReferent or IfcRelNests -- it only mutates the StartTag/EndTag string attributes already
+    present on each segment's DesignParameters.
+
+    Every real segment's StartTag is set to a computed tag describing the point where it begins,
+    using the same label-and-station format as update_key_point_referents' Name minus the alignment
+    name (via _get_key_point_tag), e.g. "145+98.32 (P.C.)". The first segment's StartTag comes from
+    the "Beginning of Alignment" boundary label.
+
+    EndTag is left untouched unless `label_end_tag` is True. When enabled, for each transition
+    between two consecutive segments, the outgoing segment's EndTag is set to the same tag as the
+    incoming segment's StartTag (they describe the same physical point), and the last segment's
+    EndTag is set from the "End of Alignment" boundary label.
+
+    Labels come from _get_segment_start_point_label -- if a callback has been registered via
+    register_referent_name_callback(), its output is used instead of the built-in labels, exactly as
+    in update_key_point_referents.
+
+    :param layout: IfcAlignmentHorizontal, IfcAlignmentVertical, or IfcAlignmentCant
+    :param label_end_tag: if True, also sets EndTag on every real segment. If False (default),
+        EndTag is left untouched.
+    :return: None -- this function mutates segment.DesignParameters.StartTag/EndTag in place
+
+    Example:
+
+    .. code:: python
+
+        horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+        ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(model, horizontal)
+    """
+
+    expected_types = ["IfcAlignmentHorizontal", "IfcAlignmentVertical", "IfcAlignmentCant"]
+    if not layout.is_a() in expected_types:
+        raise TypeError(
+            f"Expected entity type to be one of {[_ for _ in expected_types]}, instead received {layout.is_a()}"
+        )
+
+    alignment = ifcopenshell.api.alignment.get_alignment(layout)
+    if alignment is None:
+        raise ValueError(f"{layout.is_a()} #{layout.id()} is not nested under an IfcAlignment.")
+
+    segments = list(ifcopenshell.api.alignment.get_layout_segments(layout))
+    if segments and ifcopenshell.api.alignment.has_zero_length_segment(layout):
+        segments = segments[:-1]
+
+    if not segments:
+        return
+
+    start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
+    is_horizontal = layout.is_a("IfcAlignmentHorizontal")
+
+    distance_along = 0.0
+    prev_segment = None
+    for segment in segments:
+        dp = segment.DesignParameters
+        seg_distance_along = distance_along if is_horizontal else dp.StartDistAlong
+
+        label = _get_segment_start_point_label(prev_segment, segment)
+        station = start_station + seg_distance_along
+        tag = _get_key_point_tag(file, label, station)
+
+        dp.StartTag = tag
+        if prev_segment is not None and label_end_tag:
+            prev_segment.DesignParameters.EndTag = tag
+
+        if is_horizontal:
+            distance_along += dp.SegmentLength
+        else:
+            distance_along = dp.StartDistAlong + dp.HorizontalLength
+
+        prev_segment = segment
+
+    if label_end_tag:
+        label = _get_segment_start_point_label(prev_segment, None)
+        station = start_station + distance_along
+        prev_segment.DesignParameters.EndTag = _get_key_point_tag(file, label, station)

src/ifcopenshell-python/ifcopenshell/api/alignment/update_key_point_referents.py

@@ -22,9 +22,9 @@ import ifcopenshell
 import ifcopenshell.api.alignment
 import ifcopenshell.api.pset
 import ifcopenshell.guid
-import ifcopenshell.util.alignment
 import ifcopenshell.util.element
 from ifcopenshell import entity_instance
+from ifcopenshell.api.alignment._get_key_point_tag import _get_key_point_tag
 from ifcopenshell.api.alignment._get_segment_start_point_label import (
     _get_segment_start_point_label,
 )
@@ -32,21 +32,6 @@ from ifcopenshell.api.alignment._sort_nest import _sort_nest
 from ifcopenshell.api.alignment.update_fallback_position import update_fallback_position
 
 
-def _get_key_point_referent_nest(layout: entity_instance) -> Optional[entity_instance]:
-    """
-    Searches layout.IsNestedBy for the IfcRelNests whose RelatedObjects are IfcReferent.
-
-    This is distinct from both get_stationing_nest (scoped to the parent IfcAlignment, and
-    specifically the STATION/station-equation nest) and get_alignment_segment_nest (the *segment*
-    nest that also lives on layout.IsNestedBy, holding IfcAlignmentSegment, never IfcReferent).
-    """
-    for nest in layout.IsNestedBy:
-        for related_object in nest.RelatedObjects:
-            if related_object.is_a("IfcReferent"):
-                return nest
-    return None
-
-
 def _remove_referent(file: ifcopenshell.file, referent: entity_instance) -> None:
     """Cleanly deletes a key-point IfcReferent: its Pset_Stationing, its ObjectPlacement (if
     exclusively owned by it), and finally the referent itself."""
@@ -91,7 +76,7 @@ def _create_key_point_referent(
             ),
         )
 
-    name = f"{label} ({ifcopenshell.util.alignment.station_as_string(file, station)})"
+    name = f"{alignment.Name} {_get_key_point_tag(file, label, station)}"
 
     referent = file.createIfcReferent(
         GlobalId=ifcopenshell.guid.new(),
@@ -120,7 +105,8 @@ def update_key_point_referents(
     Creates IfcReferent key-point markers for every segment transition in an alignment layout.
 
     Labels are derived from _get_segment_start_point_label (e.g. "P.C.", "P.T.", "P.O.B.",
-    "P.V.C.", ...), with the station appended, e.g. "P.C. (145+98.32)". Different jurisdictions use
+    "P.V.C.", ...), and combined with the alignment name and station to build the Name, e.g.
+    "MyAlignment 145+98.32 (P.C.)". Different jurisdictions use
     different naming systems for these key points -- register_referent_name_callback() lets a
     caller override the default horizontal/vertical/cant labeling before calling this function; if
     a callback is registered, its output is used here instead of the built-in labels. Referents are
@@ -129,9 +115,11 @@ def update_key_point_referents(
     get_stationing_nest) -- key-point referents never belong in either of those.
 
     :param layout: IfcAlignmentHorizontal, IfcAlignmentVertical, or IfcAlignmentCant
-    :param rel_nests: an existing IfcRelNests to (re)populate. May live anywhere (e.g. the parent
-        IfcAlignment, the layout, or elsewhere) -- the caller decides. If omitted, an existing
-        referent-nest already on `layout` is reused, or a new one is created and related to `layout`.
+    :param rel_nests: an existing IfcRelNests to (re)populate; its RelatingObject must be the
+        IfcAlignment that nests `layout` (TypeError is raised otherwise). If omitted, a new
+        IfcRelNests is always created and related to that IfcAlignment -- there is no implicit
+        search for or reuse of a previously created nest. Callers who want to regenerate into an
+        existing nest must pass it back in explicitly via `rel_nests`.
     :param clear: if True, deletes all IfcReferent currently in rel_nests.RelatedObjects (and their
         Pset_Stationing) before regenerating. If False (default), new referents are appended to
         whatever already exists -- no deduplication.
@@ -158,7 +146,7 @@ def update_key_point_referents(
         ifcopenshell.api.alignment.register_referent_name_callback(horizontal=my_horizontal_labels)
         horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
         nest = ifcopenshell.api.alignment.update_key_point_referents(model, horizontal)
-        # nest.RelatedObjects[0].Name starts with "Start (" instead of the default "P.O.B. ("
+        # nest.RelatedObjects[0].Name ends with "(Start)" instead of the default "(P.O.B.)"
     """
 
     expected_types = ["IfcAlignmentHorizontal", "IfcAlignmentVertical", "IfcAlignmentCant"]
@@ -167,12 +155,20 @@ def update_key_point_referents(
             f"Expected entity type to be one of {[_ for _ in expected_types]}, instead received {layout.is_a()}"
         )
 
-    if rel_nests is None:
-        rel_nests = _get_key_point_referent_nest(layout)
-        if rel_nests is None:
-            rel_nests = file.createIfcRelNests(
-                GlobalId=ifcopenshell.guid.new(), RelatingObject=layout, RelatedObjects=()
+    alignment = ifcopenshell.api.alignment.get_alignment(layout)
+    if alignment is None:
+        raise ValueError(f"{layout.is_a()} #{layout.id()} is not nested under an IfcAlignment.")
+
+    if rel_nests is not None:
+        if not rel_nests.RelatingObject.is_a("IfcAlignment"):
+            raise TypeError(
+                f"Expected rel_nests.RelatingObject to be IfcAlignment, instead received "
+                f"{rel_nests.RelatingObject.is_a()}"
             )
+    else:
+        rel_nests = file.createIfcRelNests(
+            GlobalId=ifcopenshell.guid.new(), RelatingObject=alignment, RelatedObjects=()
+        )
 
     if clear:
         for referent in list(rel_nests.RelatedObjects):
@@ -189,7 +185,6 @@ def update_key_point_referents(
         )
         return rel_nests
 
-    alignment = ifcopenshell.api.alignment.get_alignment(layout)
     start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
     curve = ifcopenshell.api.alignment.get_layout_curve(layout)
     is_horizontal = layout.is_a("IfcAlignmentHorizontal")

src/ifcopenshell-python/ifcopenshell/api/sequence/create_baseline.py

@@ -28,7 +28,7 @@ import ifcopenshell.util.sequence
 
 def create_baseline(
     file: ifcopenshell.file, work_schedule: ifcopenshell.entity_instance, name: Optional[str] = None
-) -> None:
+) -> ifcopenshell.entity_instance:
     """Creates a baseline for your Work Schedule
 
     Using a IfcWorkSchdule having PredefinedType=PLANNED,
@@ -42,7 +42,7 @@ def create_baseline(
     * Same Construction Resources
     * Same Resource Relationships
 
-    :param work_schedule: The planned work_schedule to baseline
+    :param work_schedule: The planned work schedule to baseline
     :param name: baseline work schedule name
     :return: The baseline work_schedule
 
@@ -51,7 +51,7 @@ def create_baseline(
     .. code:: python
 
         # We have a Work Schedule
-        planned_work_schedule = WorkSchedule(name="Design new feature",predefinedType="PLANNED", deadline="2023-03-01")
+        planned_work_schedule = ifcopenshell.api.sequence.add_work_schedule(model, name="Planned Construction Schedule")
 
         # And now we have a baseline for our Work Schedule
         baseline_work_schedule = ifcopenshell.api.sequence.create_baseline(file, work_schedule=planned_work_schedule, name="Baseline 1")
@@ -64,24 +64,23 @@ def create_baseline(
 class Usecase:
     file: ifcopenshell.file
 
-    def execute(self, work_schedule: ifcopenshell.entity_instance, name: Union[str, None]) -> None:
-        # create work schedule
-        if not work_schedule.PredefinedType == "PLANNED":
-            return
+    def execute(
+        self, work_schedule: ifcopenshell.entity_instance, name: Union[str, None]
+    ) -> ifcopenshell.entity_instance:
+        if work_schedule.PredefinedType != "PLANNED":
+            raise ValueError("Only a PLANNED work schedule can be baselined.")
         baseline_work_schedule = ifcopenshell.api.sequence.add_work_schedule(
-            self.file, name=work_schedule.Name, predefined_type="BASELINE"
+            self.file, name=name or work_schedule.Name, predefined_type="BASELINE"
         )
-        baseline_work_schedule.Name = name
         self.create_baseline_reference(work_schedule, baseline_work_schedule)
         for summary_task in ifcopenshell.util.sequence.get_root_tasks(work_schedule):
-            res = ifcopenshell.api.sequence.duplicate_task(self.file, task=summary_task)
-            assert isinstance(res, list)
-            current, duplicate = res
+            current, duplicate = ifcopenshell.api.sequence.duplicate_task(self.file, task=summary_task)
             ifcopenshell.api.control.assign_control(
                 self.file, relating_control=baseline_work_schedule, related_objects=[duplicate[0]]
             )
             for i, task in enumerate(current):
                 self.create_baseline_reference(task, duplicate[i])
+        return baseline_work_schedule
 
     def create_baseline_reference(
         self, relating_object: ifcopenshell.entity_instance, related_object: ifcopenshell.entity_instance

src/ifcopenshell-python/ifcopenshell/util/unit.py

@@ -720,7 +720,29 @@ def calculate_unit_scale(ifc_file: ifcopenshell.file, unit_type: str = "LENGTHUN
             unit_scale *= conversion_factor.ValueComponent.wrappedValue
             unit = conversion_factor.UnitComponent
         if unit.is_a("IfcSIUnit"):
-            unit_scale *= get_prefix_multiplier(unit.Prefix)
+            prefix_multiplier = get_prefix_multiplier(unit.Prefix)
+            # An SI prefix attaches to the base unit symbol, and the prefixed
+            # symbol is raised to the power as a whole: dm3 = (dm)3 = 1e-3 m3,
+            # not 0.1 m3. For units whose dimensions are a pure power of length
+            # (METRE, SQUARE_METRE, CUBIC_METRE) the prefix multiplier must
+            # therefore be raised to the length exponent. Units with mixed or
+            # non-length dimensions (PASCAL, NEWTON, GRAM, ...) keep the linear
+            # multiplier, as there the prefix scales the derived unit itself.
+            # https://github.com/IfcOpenShell/IfcOpenShell/issues/9278
+            dimensions = unit.Dimensions
+            length_exponent = dimensions.LengthExponent
+            if length_exponent > 0 and not any(
+                (
+                    dimensions.MassExponent,
+                    dimensions.TimeExponent,
+                    dimensions.ElectricCurrentExponent,
+                    dimensions.ThermodynamicTemperatureExponent,
+                    dimensions.AmountOfSubstanceExponent,
+                    dimensions.LuminousIntensityExponent,
+                )
+            ):
+                prefix_multiplier **= length_exponent
+            unit_scale *= prefix_multiplier
     return unit_scale
 
 
@@ -940,7 +962,8 @@ def convert_file_length_units(ifc_file: ifcopenshell.file, target_units: str = "
         )
 
     unit_assignment = get_unit_assignment(file_patched)
-    unit_assignment.Units = [new_length, *(u for u in unit_assignment.Units if u.UnitType != new_length.UnitType)]
+    # UnitType not available on IfcMonetaryUnit
+    unit_assignment.Units = [new_length, *(u for u in unit_assignment.Units if getattr(u, 'UnitType', None) != new_length.UnitType)]
     if not file_patched.get_total_inverses(old_length):
         ifcopenshell.util.element.remove_deep2(file_patched, old_length)
 

src/ifcopenshell-python/test/api/alignment/test_referent_names.py

@@ -96,6 +96,10 @@ def callback_alignment():
     yield alignment
 
 
+def _label(name):
+    return name.rsplit("(", 1)[1].rstrip(")")
+
+
 def test_with_default_names(default_names_alignment):
     file = default_names_alignment.file
     horizontal = ifcopenshell.api.alignment.get_horizontal_layout(default_names_alignment)
@@ -107,8 +111,8 @@ def test_with_default_names(default_names_alignment):
     expected_h = ["P.O.B.", "P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T.", "P.O.E."]
     expected_v = ["V.P.O.B.", "P.V.C.", "P.V.T.", "P.V.C.", "P.V.T.", "P.V.C.", "P.V.T.", "P.V.C.", "P.V.T.", "V.P.O.E."]
 
-    assert [r.Name.split(" (")[0] for r in h_nest.RelatedObjects] == expected_h
-    assert [r.Name.split(" (")[0] for r in v_nest.RelatedObjects] == expected_v
+    assert [_label(r.Name) for r in h_nest.RelatedObjects] == expected_h
+    assert [_label(r.Name) for r in v_nest.RelatedObjects] == expected_v
 
 
 def test_with_callbacks(callback_alignment):
@@ -122,7 +126,7 @@ def test_with_callbacks(callback_alignment):
     expected_h = ["A", "Q", "Q", "Q", "Q", "Q", "Q", "Z"]
     expected_v = ["a", "q", "q", "q", "q", "q", "q", "q", "q", "z"]
 
-    assert [r.Name.split(" (")[0] for r in h_nest.RelatedObjects] == expected_h
-    assert [r.Name.split(" (")[0] for r in v_nest.RelatedObjects] == expected_v
+    assert [_label(r.Name) for r in h_nest.RelatedObjects] == expected_h
+    assert [_label(r.Name) for r in v_nest.RelatedObjects] == expected_v
 
     ifcopenshell.api.alignment.register_referent_name_callback(None, None, None)  # reset global state

src/ifcopenshell-python/test/api/alignment/test_update_alignment_parameter_segment_tags.py

@@ -0,0 +1,307 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.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 ifcopenshell.api.alignment
+import ifcopenshell.api.context
+import ifcopenshell.api.unit
+import ifcopenshell.util.alignment
+
+COORDINATES = [(500.0, 2500.0), (3340.0, 660.0), (4340.0, 5000.0), (7600.0, 4560.0), (8480.0, 2010.0)]
+RADII = [1000.0, 1250.0, 950.0]
+VPOINTS = [(0.0, 100.0), (2000.0, 135.0), (5000.0, 105.0), (7400.0, 153.0), (9800.0, 105.0), (12800.0, 90.0)]
+LENGTHS = [1600.0, 1200.0, 2000.0, 800.0]
+
+
+def _new_file():
+    file = ifcopenshell.file(schema="IFC4X3")
+    file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_si_unit(file, unit_type="LENGTHUNIT")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    geometric_representation_context = ifcopenshell.api.context.add_context(file, context_type="Model")
+    ifcopenshell.api.context.add_context(
+        file,
+        context_type="Model",
+        context_identifier="Axis",
+        target_view="MODEL_VIEW",
+        parent=geometric_representation_context,
+    )
+    return file
+
+
+def _new_file_no_context():
+    file = ifcopenshell.file(schema="IFC4X3")
+    file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_si_unit(file, unit_type="LENGTHUNIT")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    return file
+
+
+def _build_alignment(file, start_station=0.0):
+    return ifcopenshell.api.alignment.create_by_pi_method(
+        file, "TestAlignment", COORDINATES, RADII, VPOINTS, LENGTHS, start_station
+    )
+
+
+def _real_segments(layout):
+    segments = ifcopenshell.api.alignment.get_layout_segments(layout)
+    return segments[:-1] if ifcopenshell.api.alignment.has_zero_length_segment(layout) else segments
+
+
+def _label(tag):
+    return tag.rsplit("(", 1)[1].rstrip(")")
+
+
+def test_wrong_layout_type_raises_type_error():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    with pytest.raises(TypeError):
+        ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, alignment)
+
+
+def test_not_nested_under_alignment_raises_value_error():
+    file = _new_file_no_context()
+    horizontal = file.createIfcAlignmentHorizontal(GlobalId=ifcopenshell.guid.new())
+    with pytest.raises(ValueError):
+        ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+
+def test_returns_none():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    result = ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    assert result is None
+
+
+def test_no_referents_or_rel_nests_created():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    referents_before = len(file.by_type("IfcReferent"))
+    rel_nests_before = len(file.by_type("IfcRelNests"))
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    assert len(file.by_type("IfcReferent")) == referents_before
+    assert len(file.by_type("IfcRelNests")) == rel_nests_before
+
+
+def test_no_real_segments_leaves_tags_none():
+    file = _new_file_no_context()
+    alignment = ifcopenshell.api.alignment.create(file, "A1", include_geometry=False)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    result = ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    assert result is None
+    segments = ifcopenshell.api.alignment.get_layout_segments(horizontal)
+    assert len(segments) == 1  # only the auto zero-length segment
+    assert segments[0].DesignParameters.StartTag is None
+    assert segments[0].DesignParameters.EndTag is None
+
+
+def test_single_real_segment_produces_only_boundary_tags():
+    file = _new_file_no_context()
+    alignment = ifcopenshell.api.alignment.create(file, "A1", include_geometry=False)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    design_parameters = file.createIfcAlignmentHorizontalSegment(
+        StartTag=None,
+        EndTag=None,
+        StartPoint=file.createIfcCartesianPoint((0.0, 0.0)),
+        StartDirection=0.0,
+        StartRadiusOfCurvature=0.0,
+        EndRadiusOfCurvature=0.0,
+        SegmentLength=100.0,
+        GravityCenterLineHeight=None,
+        PredefinedType="LINE",
+    )
+    ifcopenshell.api.alignment.create_layout_segment(file, horizontal, design_parameters)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal, label_end_tag=True)
+
+    segments = _real_segments(horizontal)
+    assert len(segments) == 1
+    dp = segments[0].DesignParameters
+    assert _label(dp.StartTag) == "P.O.B."
+    assert _label(dp.EndTag) == "P.O.E."
+
+
+def test_end_tag_not_labelled_by_default():
+    file = _new_file_no_context()
+    alignment = ifcopenshell.api.alignment.create(file, "A1", include_geometry=False)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    design_parameters = file.createIfcAlignmentHorizontalSegment(
+        StartTag=None,
+        EndTag=None,
+        StartPoint=file.createIfcCartesianPoint((0.0, 0.0)),
+        StartDirection=0.0,
+        StartRadiusOfCurvature=0.0,
+        EndRadiusOfCurvature=0.0,
+        SegmentLength=100.0,
+        GravityCenterLineHeight=None,
+        PredefinedType="LINE",
+    )
+    ifcopenshell.api.alignment.create_layout_segment(file, horizontal, design_parameters)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    segments = _real_segments(horizontal)
+    assert len(segments) == 1
+    dp = segments[0].DesignParameters
+    assert _label(dp.StartTag) == "P.O.B."
+    assert dp.EndTag is None
+
+
+def test_horizontal_tag_labels_and_adjacency():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal, label_end_tag=True)
+
+    segments = _real_segments(horizontal)
+    assert len(segments) == 7
+
+    start_labels = [_label(s.DesignParameters.StartTag) for s in segments]
+    end_labels = [_label(s.DesignParameters.EndTag) for s in segments]
+
+    assert start_labels == ["P.O.B.", "P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T."]
+    assert end_labels == ["P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T.", "P.O.E."]
+
+    # every real segment has both tags set
+    assert all(s.DesignParameters.StartTag is not None for s in segments)
+    assert all(s.DesignParameters.EndTag is not None for s in segments)
+
+    # adjacent segments agree on the tag describing their shared transition point
+    for i in range(len(segments) - 1):
+        assert segments[i].DesignParameters.EndTag == segments[i + 1].DesignParameters.StartTag
+
+
+def test_vertical_tag_labels_and_adjacency():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    vertical = ifcopenshell.api.alignment.get_vertical_layout(alignment)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, vertical, label_end_tag=True)
+
+    segments = _real_segments(vertical)
+    assert len(segments) == 9
+
+    start_labels = [_label(s.DesignParameters.StartTag) for s in segments]
+    end_labels = [_label(s.DesignParameters.EndTag) for s in segments]
+
+    assert start_labels == [
+        "V.P.O.B.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+    ]
+    assert end_labels == [
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "V.P.O.E.",
+    ]
+
+    assert all(s.DesignParameters.StartTag is not None for s in segments)
+    assert all(s.DesignParameters.EndTag is not None for s in segments)
+
+    for i in range(len(segments) - 1):
+        assert segments[i].DesignParameters.EndTag == segments[i + 1].DesignParameters.StartTag
+
+
+def test_cant_layout_boundary_tags():
+    file = _new_file_no_context()
+    alignment = ifcopenshell.api.alignment.create(file, "A1", include_cant=True, include_geometry=False)
+    cant = ifcopenshell.api.alignment.get_cant_layout(alignment)
+
+    dp1 = file.createIfcAlignmentCantSegment(
+        StartDistAlong=0.0,
+        HorizontalLength=100.0,
+        StartCantLeft=0.0,
+        EndCantLeft=0.0,
+        StartCantRight=0.0,
+        EndCantRight=0.0,
+        PredefinedType="CONSTANTCANT",
+    )
+    ifcopenshell.api.alignment.create_layout_segment(file, cant, dp1)
+
+    dp2 = file.createIfcAlignmentCantSegment(
+        StartDistAlong=100.0,
+        HorizontalLength=50.0,
+        StartCantLeft=0.0,
+        EndCantLeft=0.0,
+        StartCantRight=0.0,
+        EndCantRight=0.0,
+        PredefinedType="CONSTANTCANT",
+    )
+    ifcopenshell.api.alignment.create_layout_segment(file, cant, dp2)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, cant, label_end_tag=True)
+
+    segments = _real_segments(cant)
+    assert _label(segments[0].DesignParameters.StartTag) == "C.P.O.B."
+    assert _label(segments[-1].DesignParameters.EndTag) == "C.P.O.E."
+    # CONSTANTCANT -> CONSTANTCANT is currently an unfilled "xx" placeholder in the cant lookup
+    # table (_get_segment_start_point_label.py) -- out of scope to fill in here.
+    assert _label(segments[0].DesignParameters.EndTag) == "xx"
+    assert _label(segments[-1].DesignParameters.StartTag) == "xx"
+
+
+def test_exact_tag_format():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
+    segments = _real_segments(horizontal)
+    assert segments[0].DesignParameters.StartTag == (
+        f"{ifcopenshell.util.alignment.station_as_string(file, start_station)} (P.O.B.)"
+    )
+
+
+test_wrong_layout_type_raises_type_error()
+test_not_nested_under_alignment_raises_value_error()
+test_returns_none()
+test_no_referents_or_rel_nests_created()
+test_no_real_segments_leaves_tags_none()
+test_single_real_segment_produces_only_boundary_tags()
+test_end_tag_not_labelled_by_default()
+test_horizontal_tag_labels_and_adjacency()
+test_vertical_tag_labels_and_adjacency()
+test_cant_layout_boundary_tags()
+test_exact_tag_format()

src/ifcopenshell-python/test/api/alignment/test_update_key_point_referents.py

@@ -66,6 +66,10 @@ def _pset_station(referent):
     return ifcopenshell.util.element.get_pset(referent, name="Pset_Stationing", prop="Station")
 
 
+def _label(name):
+    return name.rsplit("(", 1)[1].rstrip(")")
+
+
 def test_wrong_layout_type_raises_type_error():
     file = _new_file()
     alignment = _build_alignment(file)
@@ -82,13 +86,13 @@ def test_default_rel_nests_created_when_none_provided():
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
 
     assert nest.is_a("IfcRelNests")
-    assert nest.RelatingObject == horizontal
+    assert nest.RelatingObject == alignment
     assert nest.id() != segment_nest.id()
     assert len(nest.RelatedObjects) == 8
     assert all(r.is_a("IfcReferent") for r in nest.RelatedObjects)
 
 
-def test_second_call_without_rel_nests_reuses_existing_nest():
+def test_second_call_without_rel_nests_creates_separate_nest():
     file = _new_file()
     alignment = _build_alignment(file)
     horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
@@ -97,18 +101,31 @@ def test_second_call_without_rel_nests_reuses_existing_nest():
     nest1 = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
     nest2 = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
 
-    assert nest1.id() == nest2.id()
-    assert len(nest2.RelatedObjects) == 16
+    assert nest1.id() != nest2.id()
+    assert len(nest1.RelatedObjects) == 8
+    assert len(nest2.RelatedObjects) == 8
     segment_count_after = len(ifcopenshell.api.alignment.get_alignment_segment_nest(horizontal).RelatedObjects)
     assert segment_count_after == segment_count_before
 
 
+def test_passing_previous_nest_back_in_accumulates():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    nest1 = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
+    nest2 = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal, rel_nests=nest1)
+
+    assert nest1.id() == nest2.id()
+    assert len(nest2.RelatedObjects) == 16
+
+
 def test_provided_rel_nests_is_used_as_is():
     file = _new_file()
     alignment = _build_alignment(file)
     horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
 
-    # the nest may live anywhere the caller chooses, e.g. hung off the parent IfcAlignment
+    # rel_nests.RelatingObject must be the IfcAlignment that nests `layout`
     rel_nests = file.createIfcRelNests(GlobalId=ifcopenshell.guid.new(), RelatingObject=alignment, RelatedObjects=())
 
     result = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal, rel_nests=rel_nests)
@@ -118,6 +135,17 @@ def test_provided_rel_nests_is_used_as_is():
     assert len(result.RelatedObjects) == 8
 
 
+def test_provided_rel_nests_with_wrong_relating_object_raises_type_error():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    rel_nests = file.createIfcRelNests(GlobalId=ifcopenshell.guid.new(), RelatingObject=horizontal, RelatedObjects=())
+
+    with pytest.raises(TypeError):
+        ifcopenshell.api.alignment.update_key_point_referents(file, horizontal, rel_nests=rel_nests)
+
+
 def test_clear_true_removes_old_referents_and_psets():
     file = _new_file()
     alignment = _build_alignment(file)
@@ -157,7 +185,7 @@ def test_default_horizontal_labels_and_order():
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
 
     expected = ["P.O.B.", "P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T.", "P.O.E."]
-    assert [r.Name.split(" (")[0] for r in nest.RelatedObjects] == expected
+    assert [_label(r.Name) for r in nest.RelatedObjects] == expected
 
     stations = [_pset_station(r) for r in nest.RelatedObjects]
     assert stations == sorted(stations)
@@ -183,7 +211,7 @@ def test_default_vertical_labels_and_order():
         "P.V.T.",
         "V.P.O.E.",
     ]
-    assert [r.Name.split(" (")[0] for r in nest.RelatedObjects] == expected
+    assert [_label(r.Name) for r in nest.RelatedObjects] == expected
 
     segments = ifcopenshell.api.alignment.get_layout_segments(vertical)
     real_segments = segments[:-1] if ifcopenshell.api.alignment.has_zero_length_segment(vertical) else segments
@@ -200,7 +228,7 @@ def test_name_format():
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
     referent = nest.RelatedObjects[0]
     station = _pset_station(referent)
-    assert referent.Name == f"P.O.B. ({ifcopenshell.util.alignment.station_as_string(file, station)})"
+    assert referent.Name == f"{alignment.Name} {ifcopenshell.util.alignment.station_as_string(file, station)} (P.O.B.)"
 
 
 def test_geometric_placement_when_layout_has_representation():
@@ -268,7 +296,7 @@ def test_cant_layout_boundary_labels():
 
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, cant)
 
-    labels = [r.Name.split(" (")[0] for r in nest.RelatedObjects]
+    labels = [_label(r.Name) for r in nest.RelatedObjects]
     assert labels[0] == "C.P.O.B."
     assert labels[-1] == "C.P.O.E."
     # CONSTANTCANT -> CONSTANTCANT is currently an unfilled "xx" placeholder in the cant lookup
@@ -307,7 +335,7 @@ def test_single_real_segment_produces_only_boundary_labels():
     ifcopenshell.api.alignment.create_layout_segment(file, horizontal, design_parameters)
 
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
-    labels = [r.Name.split(" (")[0] for r in nest.RelatedObjects]
+    labels = [_label(r.Name) for r in nest.RelatedObjects]
     assert labels == ["P.O.B.", "P.O.E."]
 
 
@@ -356,8 +384,10 @@ def test_returns_ifc_rel_nests():
 
 test_wrong_layout_type_raises_type_error()
 test_default_rel_nests_created_when_none_provided()
-test_second_call_without_rel_nests_reuses_existing_nest()
+test_second_call_without_rel_nests_creates_separate_nest()
+test_passing_previous_nest_back_in_accumulates()
 test_provided_rel_nests_is_used_as_is()
+test_provided_rel_nests_with_wrong_relating_object_raises_type_error()
 test_clear_true_removes_old_referents_and_psets()
 test_clear_false_appends_without_dedup()
 test_default_horizontal_labels_and_order()

src/ifcopenshell-python/test/api/sequence/test_create_baseline.py

@@ -0,0 +1,146 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2026 IfcOpenShell contributors
+#
+# 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.
+
+
+import pytest
+
+import ifcopenshell.api.root
+import ifcopenshell.api.sequence
+import ifcopenshell.util.sequence
+import test.bootstrap
+
+
+class TestCreateBaseline(test.bootstrap.IFC4):
+    def create_planned_schedule(self, name="Design & Build"):
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+        return ifcopenshell.api.sequence.add_work_schedule(self.file, name=name, predefined_type="PLANNED")
+
+    def test_returns_the_created_baseline_schedule(self):
+        planned = self.create_planned_schedule()
+        root_task = ifcopenshell.api.sequence.add_task(self.file, work_schedule=planned, name="Design")
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+
+        assert baseline.is_a("IfcWorkSchedule")
+        assert baseline.Name == "Baseline 1"
+        assert baseline.PredefinedType == "BASELINE"
+        baseline_roots = ifcopenshell.util.sequence.get_root_tasks(baseline)
+        assert [task.Name for task in baseline_roots] == [root_task.Name]
+        assert baseline_roots != [root_task]
+
+    def test_falls_back_to_the_planned_schedule_name(self):
+        planned = self.create_planned_schedule()
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned)
+
+        assert baseline.Name == "Design & Build"
+
+    def test_leaves_the_name_null_when_both_names_are_omitted(self):
+        planned = self.create_planned_schedule()
+        planned.Name = None
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned)
+
+        assert baseline.Name is None
+
+    def test_rejects_a_non_planned_schedule(self):
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+        actual = ifcopenshell.api.sequence.add_work_schedule(self.file, predefined_type="ACTUAL")
+
+        with pytest.raises(ValueError):
+            ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=actual)
+
+    def test_baselines_a_schedule_without_tasks(self):
+        planned = self.create_planned_schedule()
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+
+        assert ifcopenshell.util.sequence.get_root_tasks(baseline) == []
+
+    def test_baselines_every_root_task(self):
+        planned = self.create_planned_schedule()
+        ifcopenshell.api.sequence.add_task(self.file, work_schedule=planned, name="Design")
+        ifcopenshell.api.sequence.add_task(self.file, work_schedule=planned, name="Construction")
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+
+        baseline_roots = ifcopenshell.util.sequence.get_root_tasks(baseline)
+        assert sorted(task.Name for task in baseline_roots) == ["Construction", "Design"]
+
+    def test_baselines_nested_tasks(self):
+        planned = self.create_planned_schedule()
+        root_task = ifcopenshell.api.sequence.add_task(self.file, work_schedule=planned, name="Construction")
+        ifcopenshell.api.sequence.add_task(self.file, parent_task=root_task, name="Foundations")
+        ifcopenshell.api.sequence.add_task(self.file, parent_task=root_task, name="Superstructure")
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+
+        baseline_root = ifcopenshell.util.sequence.get_root_tasks(baseline)[0]
+        nested = ifcopenshell.util.sequence.get_nested_tasks(baseline_root)
+        assert sorted(task.Name for task in nested) == ["Foundations", "Superstructure"]
+        assert len(self.file.by_type("IfcTask")) == 6
+
+    def test_baselines_task_attributes_and_times(self):
+        planned = self.create_planned_schedule()
+        task = ifcopenshell.api.sequence.add_task(
+            self.file, work_schedule=planned, name="Foundations", identification="A1", description="Pour concrete"
+        )
+        ifcopenshell.api.sequence.add_task_time(self.file, task=task)
+        ifcopenshell.api.sequence.edit_task_time(
+            self.file, task_time=task.TaskTime, attributes={"ScheduleDuration": "P5D"}
+        )
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+
+        baseline_task = ifcopenshell.util.sequence.get_root_tasks(baseline)[0]
+        assert baseline_task.Identification == "A1"
+        assert baseline_task.Description == "Pour concrete"
+        assert baseline_task.TaskTime != task.TaskTime
+        assert baseline_task.TaskTime.ScheduleDuration == "P5D"
+
+    def test_baselines_sequence_relationships_between_tasks(self):
+        planned = self.create_planned_schedule()
+        root_task = ifcopenshell.api.sequence.add_task(self.file, work_schedule=planned, name="Construction")
+        predecessor = ifcopenshell.api.sequence.add_task(self.file, parent_task=root_task, name="Foundations")
+        successor = ifcopenshell.api.sequence.add_task(self.file, parent_task=root_task, name="Superstructure")
+        ifcopenshell.api.sequence.assign_sequence(self.file, relating_process=predecessor, related_process=successor)
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+
+        baseline_root = ifcopenshell.util.sequence.get_root_tasks(baseline)[0]
+        nested = {task.Name: task for task in ifcopenshell.util.sequence.get_nested_tasks(baseline_root)}
+        rels = nested["Foundations"].IsPredecessorTo
+        assert len(rels) == 1
+        assert rels[0].RelatedProcess == nested["Superstructure"]
+
+    def test_references_the_planned_schedule_and_tasks(self):
+        planned = self.create_planned_schedule()
+        root_task = ifcopenshell.api.sequence.add_task(self.file, work_schedule=planned, name="Construction")
+        subtask = ifcopenshell.api.sequence.add_task(self.file, parent_task=root_task, name="Foundations")
+
+        baseline = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+
+        baseline_root = ifcopenshell.util.sequence.get_root_tasks(baseline)[0]
+        baseline_subtask = ifcopenshell.util.sequence.get_nested_tasks(baseline_root)[0]
+        references = {
+            rel.RelatingObject: list(rel.RelatedObjects) for rel in self.file.by_type("IfcRelDefinesByObject")
+        }
+        assert references[planned] == [baseline]
+        assert references[root_task] == [baseline_root]
+        assert references[subtask] == [baseline_subtask]
+
+    def test_reuses_the_existing_reference_for_further_baselines(self):
+        planned = self.create_planned_schedule()
+
+        first = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 1")
+        second = ifcopenshell.api.sequence.create_baseline(self.file, work_schedule=planned, name="Baseline 2")
+
+        assert len(planned.Declares) == 1
+        assert list(planned.Declares[0].RelatedObjects) == [first, second]

src/ifcopenshell-python/test/util/test_unit.py

@@ -200,6 +200,31 @@ class TestCalculateUnitScale(test.bootstrap.IFC4):
         ifcopenshell.api.unit.assign_unit(self.file, units=[angle])
         assert subject.calculate_unit_scale(self.file, "PLANEANGLEUNIT") == pi / 180 * 0.001
 
+    def test_prefix_is_raised_to_the_length_exponent_for_area_and_volume(self):
+        # A prefixed square/cubic metre is (prefix-metre) squared/cubed:
+        # DECI SQUARE_METRE = dm2 = 1e-2 m2, DECI CUBIC_METRE = dm3 (litre) = 1e-3 m3.
+        # https://github.com/IfcOpenShell/IfcOpenShell/issues/9278
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+        area = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="AREAUNIT")
+        area.Prefix = "DECI"
+        volume = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="VOLUMEUNIT")
+        volume.Prefix = "DECI"
+        ifcopenshell.api.unit.assign_unit(self.file, units=[area, volume])
+        assert subject.calculate_unit_scale(self.file, "AREAUNIT") == pytest.approx(0.1**2)
+        assert subject.calculate_unit_scale(self.file, "VOLUMEUNIT") == pytest.approx(0.1**3)
+
+    def test_prefix_stays_linear_for_units_that_are_not_a_pure_power_of_length(self):
+        # For derived and non-length SI units the prefix scales the unit itself:
+        # KILO PASCAL = 1e3 Pa, KILO GRAM = 1e3 g.
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+        pressure = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="PRESSUREUNIT")
+        pressure.Prefix = "KILO"
+        mass = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="MASSUNIT")
+        mass.Prefix = "KILO"
+        ifcopenshell.api.unit.assign_unit(self.file, units=[pressure, mass])
+        assert subject.calculate_unit_scale(self.file, "PRESSUREUNIT") == pytest.approx(1000)
+        assert subject.calculate_unit_scale(self.file, "MASSUNIT") == pytest.approx(1000)
+
 
 class TestFormatLength(test.bootstrap.IFC4):
     def test_run(self):