diff --git a/src/ifcopenshell-python/ifcopenshell/express/header.py b/src/ifcopenshell-python/ifcopenshell/express/header.py
index 6541aae3e9..cc403c8f70 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/header.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/header.py
@@ -77,13 +77,10 @@ class Header(codegen.Base):
                     attr_lines = []
 
                     def write_method(attr):
-                        if attr.optional:
-                            attr_lines.append(templates.optional_attribute_description % (attr.name, name))
-                            attr_lines.append("bool has%s() const;" % (attr.name))
                         attr_lines.extend(
                             ["/// %s" % d for d in documentation.description(".".join((name, attr.name)))]
                         )
-                        type_str = mapping.get_parameter_type(attr, allow_optional=False, allow_entities=False)
+                        type_str = mapping.get_parameter_type(attr)
                         if mapping.make_argument_type(attr) != "IfcUtil::Argument_UNKNOWN":
                             attr_lines.append("%s %s() const;" % (type_str, attr.name))
                             attr_lines.append("void set%s(%s v);" % (attr.name, type_str))
diff --git a/src/ifcopenshell-python/ifcopenshell/express/implementation.py b/src/ifcopenshell-python/ifcopenshell/express/implementation.py
index e4f2522883..a27cb1aa21 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/implementation.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/implementation.py
@@ -74,17 +74,6 @@ class Implementation(codegen.Base):
             write_attr = lambda str, **kwargs: attributes.append(str % kwargs)
             for arg in constructor_arguments:
                 if not arg["is_inherited"] and not arg["is_derived"]:
-                    if arg["is_optional"]:
-                        write_attr(
-                            templates.const_function,
-                            class_name=name,
-                            schema_name=schema_name,
-                            schema_name_upper=schema_name_upper,
-                            name="has%s" % arg["name"],
-                            arguments="",
-                            return_type="bool",
-                            body=templates.optional_attr_stmt % {"index": arg["index"] - 1},
-                        )
 
                     def find_template(arg):
                         simple = mapping.schema.is_simpletype(arg["list_instance_type"])
@@ -111,11 +100,12 @@ class Implementation(codegen.Base):
                         arguments="",
                         schema_name=schema_name,
                         schema_name_upper=schema_name_upper,
-                        return_type=arg["non_optional_type"],
+                        return_type=arg["full_type"],
                         body=tmpl
                         % {
                             "index": arg["index"] - 1,
-                            "type": arg["non_optional_type"].replace("::Value", ""),
+                            "type": arg["full_type"].replace("::Value", ""),
+                            "non_optional_type": arg["non_optional_type"].replace("::Value", ""),
                             "list_instance_type": arg["list_instance_type"],
                         },
                     )
@@ -136,12 +126,17 @@ class Implementation(codegen.Base):
                         templates.function,
                         class_name=name,
                         name="set%s" % arg["name"],
-                        arguments="%s v" % arg["non_optional_type"],
+                        arguments="%s v" % arg["full_type"],
                         return_type="void",
                         schema_name=schema_name,
                         schema_name_upper=schema_name_upper,
                         body=tmpl
-                        % {"index": arg["index"] - 1, "type": arg["non_optional_type"].replace("::Value", "")},
+                        % {
+                            "index": arg["index"] - 1, 
+                            "type": arg["full_type"].replace("::Value", ""),
+                            "non_optional_type": arg["non_optional_type"].replace("::Value", ""),
+                            "star_if_optional": "*" if arg["is_optional"] else ""
+                        },
                     )
 
                 if arg["is_derived"]:
diff --git a/src/ifcopenshell-python/ifcopenshell/express/mapping.py b/src/ifcopenshell-python/ifcopenshell/express/mapping.py
index 0c05413a2c..0a6814a652 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/mapping.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/mapping.py
@@ -28,7 +28,7 @@ class Mapping:
 
     express_to_cpp_typemapping = {
         "boolean": "bool",
-        "logical": "bool",
+        "logical": "boost::logic::tribool",
         "integer": "int",
         "real": "double",
         "number": "double",
@@ -40,6 +40,7 @@ class Mapping:
         [
             "INT",
             "BOOL",
+            "LOGICAL",
             "DOUBLE",
             "STRING",
             "BINARY",
@@ -141,7 +142,10 @@ class Mapping:
                 raise ValueError("Unable to map type %r for attribute %r" % (type, attr))
 
         ty = _make_argument_type(attr.type if hasattr(attr, "type") else attr)
+        if ty == "TRIBOOL": ty = "LOGICAL"
+        
         if ty not in self.supported_argument_types:
+            import pdb; pdb.set_trace()
             print("Attribute %r mapped as 'unknown'" % (attr), file=sys.stderr)
             ty = "UNKNOWN"
         return "IfcUtil::Argument_%s" % ty
@@ -152,7 +156,7 @@ class Mapping:
         else:
             return self.get_type_dep(type.type)
 
-    def get_parameter_type(self, attr, allow_optional, allow_entities, allow_pointer=True):
+    def get_parameter_type(self, attr, allow_optional=True):
         attr_type = self.flatten_type(attr.type)
 
         if (isinstance(attr_type, nodes.SimpleType) and isinstance(attr_type.type, nodes.StringType)) or isinstance(
@@ -168,7 +172,7 @@ class Mapping:
             type_str = "::%s::%s::Value" % (self.schema.name.capitalize(), attr_type)
         elif isinstance(type_str, nodes.AggregationType):
             is_nested_list = isinstance(attr_type.type, nodes.AggregationType)
-            ty = self.get_parameter_type(attr_type.type if is_nested_list else attr_type, False, allow_entities, False)
+            ty = self.get_parameter_type(attr_type.type if is_nested_list else attr_type)
             if self.schema.is_select(attr_type.type):
                 type_str = templates.untyped_list
             elif self.schema.is_simpletype(ty) or str(ty) in self.express_to_cpp_typemapping.values():
@@ -179,14 +183,10 @@ class Mapping:
                 tmpl = templates.list_list_type if is_nested_list else templates.list_type
                 type_str = tmpl % {"instance_type": ty}
         elif self.schema.is_entity(type_str) or self.schema.is_select(type_str):
-            type_str = "::%s::%s" % (self.schema.name.capitalize(), attr_type)
-            if allow_pointer:
-                type_str += "*"
-            is_ptr = True
-        elif not allow_pointer and self.schema.is_select(type_str):
-            type_str = "IfcUtil::IfcBaseClass*"
+            type_str = "::%s::%s*" % (self.schema.name.capitalize(), attr_type)
             is_ptr = True
         if allow_optional and attr.optional and not is_ptr:
+            # pointers are still handled with nullptr for the time being
             type_str = "boost::optional< %s >" % type_str
         return type_str
 
@@ -262,9 +262,9 @@ class Mapping:
             {
                 "index": i + 1,
                 "name": attr.name,
-                "full_type": self.get_parameter_type(attr, allow_optional=True, allow_entities=True),
-                "specialized_type": self.get_parameter_type(attr, allow_optional=True, allow_entities=False),
-                "non_optional_type": self.get_parameter_type(attr, allow_optional=False, allow_entities=False),
+                "full_type": self.get_parameter_type(attr),
+                "specialized_type": self.get_parameter_type(attr),
+                "non_optional_type": self.get_parameter_type(attr, allow_optional=False),
                 "list_instance_type": self.list_instance_type(attr),
                 "is_optional": attr.optional,
                 "is_inherited": i < num_inherited,
diff --git a/src/ifcopenshell-python/ifcopenshell/express/templates.py b/src/ifcopenshell-python/ifcopenshell/express/templates.py
index 4341c7957b..c326bd17f7 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/templates.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/templates.py
@@ -239,9 +239,9 @@ parent_type_test = " || %s::is(v)"
 
 optional_attr_stmt = "return !data_->getArgument(%(index)d)->isNull();"
 
-get_attr_stmt = "return *data_->getArgument(%(index)d);"
-get_attr_stmt_enum = "return %(type)s::FromString(*data_->getArgument(%(index)d));"
-get_attr_stmt_entity = "return (%(type)s)((IfcUtil::IfcBaseClass*)(*data_->getArgument(%(index)d)));"
+get_attr_stmt = "return (%(non_optional_type)s) *data_->getArgument(%(index)d);"
+get_attr_stmt_enum = "return %(non_optional_type)s::FromString(*data_->getArgument(%(index)d));"
+get_attr_stmt_entity = "return (%(non_optional_type)s)((IfcUtil::IfcBaseClass*)(*data_->getArgument(%(index)d)));"
 get_attr_stmt_array = (
     "IfcEntityList::ptr es = *data_->getArgument(%(index)d); return es->as< %(list_instance_type)s >();"
 )
@@ -255,7 +255,7 @@ set_attr_stmt = (
     "{IfcWrite::IfcWriteArgument* attr = new IfcWrite::IfcWriteArgument();attr->set(v"
     + ");data_->setArgument(%(index)d,attr);}"
 )
-set_attr_stmt_enum = "{IfcWrite::IfcWriteArgument* attr = new IfcWrite::IfcWriteArgument();attr->set(IfcWrite::IfcWriteArgument::EnumerationReference(v,%(type)s::ToString(v)));data_->setArgument(%(index)d,attr);}"
+set_attr_stmt_enum = "{IfcWrite::IfcWriteArgument* attr = new IfcWrite::IfcWriteArgument();attr->set(IfcWrite::IfcWriteArgument::EnumerationReference(%(star_if_optional)sv,%(non_optional_type)s::ToString(%(star_if_optional)sv)));data_->setArgument(%(index)d,attr);}"
 set_attr_stmt_array = (
     "{IfcWrite::IfcWriteArgument* attr = new IfcWrite::IfcWriteArgument();attr->set(v->generalize()"
     + ");data_->setArgument(%(index)d,attr);}"
diff --git a/src/ifcparse/Argument.h b/src/ifcparse/Argument.h
index 864a991373..7ced5b6f97 100644
--- a/src/ifcparse/Argument.h
+++ b/src/ifcparse/Argument.h
@@ -32,6 +32,7 @@
 
 #include <boost/shared_ptr.hpp>
 #include <boost/dynamic_bitset.hpp>
+#include <boost/logic/tribool.hpp>
 
 class Argument;
 class IfcEntityList;
@@ -54,6 +55,7 @@ public:
 	virtual operator int() const;
 	virtual operator bool() const;
 	virtual operator double() const;
+	virtual operator boost::logic::tribool() const;
 	virtual operator std::string() const;
 	virtual operator boost::dynamic_bitset<>() const;
 	virtual operator IfcUtil::IfcBaseClass*() const;
diff --git a/src/ifcparse/ArgumentType.h b/src/ifcparse/ArgumentType.h
index c56a2d257e..91c89f05c4 100644
--- a/src/ifcparse/ArgumentType.h
+++ b/src/ifcparse/ArgumentType.h
@@ -29,6 +29,7 @@ namespace IfcUtil {
 		Argument_DERIVED,
 		Argument_INT,
 		Argument_BOOL,
+		Argument_LOGICAL,
 		Argument_DOUBLE,
 		Argument_STRING,
 		Argument_BINARY,