#### IfcPropertyDefinition

Natural language names

##### Semantic definitions at the entity

Entity definition

The 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 definitions, and property sets..

Property definitions define information that is shared among multiple instances of objects. The assignment of the shared information to objects is handled by the IfcRelDefines relationship.

> HISTORY New Entity in IFC Release 2.0

Attribute definitions

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
| 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. |

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
IfcRoot
1 | GlobalId | IfcGloballyUniqueId | [1:1] | Assignment of a globally unique identifier within the entire software world. | X
2 | OwnerHistory | IfcOwnerHistory | [1:1] | 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. | X
3 | Name | IfcLabel | [0:1] | 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 | [0:1] | Optional description, provided for exchanging informative comments. | X
IfcPropertyDefinition
| 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. |

##### Formal representations

XSD 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(IfcPropertySetDefinition)
SUBTYPE OF (IfcRoot);
INVERSE
HasAssociations : SET [0:?] OF IfcRelAssociates FOR RelatedObjects;
END_ENTITY;

EXPRESS-G diagram

`

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