|modifications||attributes PropertyReference is_optional||Changed from False to True|
|modifications||attributes UsageName definition||Changed from IfcLabel to IfcText|
The IfcPropertyReferenceValue allows a property value to be of type of an resource level entity. The applicable entities that can be used as value references are given by the IfcObjectReferenceSelect.
HISTORY New entity in IFC1.5. Entity has been renamed from IfcObjectReference in IFC2x.
IFC4 CHANGE Attribute PropertyReference has been made OPTIONAL with upward compatibility for file based exchange.
|HasExternalReferences||SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects||Reference to an external reference, e.g. library, classification, or document information, that is associated to the property definition.|
> IFC4 CHANGE New inverse attribute.
|1||Name||IfcIdentifier||Name for this property. This label is the significant name string that defines the semantic meaning for the property.|
|2||Description||OPTIONAL IfcText||Informative text to explain the property.|
|PartOfPset||SET [0:?] OF IfcPropertySet FOR HasProperties||Reference to the IfcPropertySet by which the IfcProperty is referenced.|
> IFC4 CHANGE New inverse attribute to navigate from IfcProperty to IfcPropertySet with upward compatibility for file based exchange.
|PropertyForDependance||SET [0:?] OF IfcPropertyDependencyRelationship FOR DependingProperty||The property on whose value that of another property depends.|
|PropertyDependsOn||SET [0:?] OF IfcPropertyDependencyRelationship FOR DependantProperty||The relating property on which the value of the property depends.|
|PartOfComplex||SET [0:?] OF IfcComplexProperty FOR HasProperties||Reference to the IfcComplexProperty in which the IfcProperty is contained.|
> IFC4 CHANGE The cardinality has changed to 0..n to allow reuse of instances of IfcProperty in several IfcComplexProperty with upward compatibility for file based exchange.
|HasConstraints||SET [0:?] OF IfcResourceConstraintRelationship FOR RelatedResourceObjects||User-defined constraints for the property.|
|HasApprovals||SET [0:?] OF IfcResourceApprovalRelationship FOR RelatedResourceObjects||User-defined approvals for the property.|
|3||UsageName||OPTIONAL IfcText||Description of the use of the referenced value within the property. It is a descriptive text that may hold an expression or other additional information.|
|4||PropertyReference||OPTIONAL IfcObjectReferenceSelect||Reference to another property entity through one of the select types in the IfcObjectReferenceSelect.|
> IFC4 CHANGE The attribute has been made optional with upward compatibility for file based exchange.
ENTITY IfcPropertyReferenceValue SUBTYPE OF (IfcSimpleProperty); UsageName : OPTIONAL IfcText; PropertyReference : OPTIONAL IfcObjectReferenceSelect; END_ENTITY;