IfcPropertyDefinition

Semantic definitions at the entity

Entity definition

IfcPropertyDefinition defines the generalization of all characteristics (i.e. a grouping of individual properties), that may be assigned to objects. Currently, subtypes of IfcPropertyDefinition include property set occurrences, property set templates, and property templates.

Property set template - IfcPropertySetTemplate, a collection of property templates that determine the definition of properties used within a project context.
Property template - IfcPropertyTemplate, a single template that determines the definition of a particular property used in the same project context. The template may determine the name, description, data type, the unit, or a standard expression for each property that is based on that template.
Property set occurrence - IfcPropertySet, a set of individual properties (that may or may not be determined by a property template) holding individual values, measure types and units, and are associated to an object occurrence or object type.

NOTE The subtype hierarchy of IfcPropertyDefinition also includes statically defined property sets as IfcPreDefinedPropertySet. Those are rarely used collections of fixed attributes combined in an entity definition. The IfcPreDefinedPropertySet can not be determined by an IfcPropertySetTemplate.

NOTE Individual properties, (subtypes of IfcProperty), are currently not included in the subtype hierarchy of IfcPropertyDefinition. This anomaly is due to upward compatibility reasons with earlier releases of this standard.

Property definitions define information that is shared among multiple instances of objects, either object occurrences or object types. IfcPropertyDefinition's (by their instantiable subtypes) can participate within the following relationships:

Assignment to a project context - an HasContext relationship to IfcRelDeclares that establishes the project context in which this property definition is declared. This relationship is predominately applicable to subtypes of IfcPropertyTemplateDefinition.
Association to external resources - an HasAssociation relationship to IfcRelAssociates that refers to external sources of information (most notably a classification or document) and creates a uni-directional association. There is no dependency implied by the association.

Subtypes are included in more specific relationships, see IfcPropertySetDefinition and IfcPropertyTemplateDefinition for details.

HISTORY New entity in IFC2.0

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
	HasContext	IfcRelDeclares @RelatedDefinitions	S[0:1]		X
	HasAssociations	IfcRelAssociates @RelatedObjects	S[0:?]	Reference to the relationship IfcRelAssociates and thus to those externally defined concepts, like classifications, documents, or library information, which are associated to the property definition.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	G
IfcRoot
1	GlobalId	IfcGloballyUniqueId		Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	?	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE only the last modification in stored - either as addition, deletion or modification. IFC4 CHANGE The attribute has been changed to be OPTIONAL.	X
3	Name	IfcLabel	?	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.	X
4	Description	IfcText	?	Optional description, provided for exchanging informative comments.	X
IfcPropertyDefinition
	HasContext	IfcRelDeclares @RelatedDefinitions	S[0:1]		X
	HasAssociations	IfcRelAssociates @RelatedObjects	S[0:?]	Reference to the relationship IfcRelAssociates and thus to those externally defined concepts, like classifications, documents, or library information, which are associated to the property definition.	X

#	Concept	Template	Model View
IfcRoot
	Identity	Software Identity	General Usage
	Revision Control	Revision Control	General Usage

Formal representations

XML Specification

 <xs:element name="IfcPropertyDefinition" type="ifc:IfcPropertyDefinition" abstract="true" substitutionGroup="ifc:IfcRoot" nillable="true"/>

 <xs:complexType name="IfcPropertyDefinition" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:IfcRoot"/>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcPropertyDefinition

 ABSTRACT SUPERTYPE OF(ONEOF(IfcPropertySetDefinition, IfcPropertyTemplateDefinition))

 SUBTYPE OF (IfcRoot);

 INVERSE

  HasContext : SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;

  HasAssociations : SET [0:?] OF IfcRelAssociates FOR RelatedObjects;

END_ENTITY;

 EXPRESS-G diagram

	Merkmal - Definition
	Property Definition
	Définition de propriété

IfcPropertyDefinition

Semantic definitions at the entity

Inherited definitions from supertypes

Definitions applying to General Usage

Formal representations