#### IfcPropertySetDefinition

Natural language names

##### Semantic definitions at the entity

Entity definition

An IfcPropertySetDefinition is a generalization of property sets, that are either:

> Dynamically extendable properties, they define properties for which the IFC model only provides a kind of "meta model", to be further declared by agreement. This means no entity definition of the properties exists within the IFC model. The declaration is done by assigning a significant string value to the Name attribute of the entity as defined in the entity IfcPropertySet and at each subtype of IfcProperty, referenced by the property set.

> Statically defined properties, they define properties for which an entity definition exists within the IFC model. The semantic meaning of each statically defined property is declared by its entity type and the meaning of the properties is defined by the name of the explicit attribute.

The subtypes of the IfcPropertySetDefinition are either the dynamically extendable IfcPropertySet, or all other statically defined subtypes.

> HISTORY New Entity in IFC Release 2x

Attribute definitions

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
| PropertyDefinitionOf | IfcRelDefinesByProperties @RelatingPropertyDefinition | S[0:1] | Reference to the relation to one or many objects that are characterized by the property definition. The reference may be omitted, if the property definition is used to define a style library and no instances, to which the particular style of property set is associated, exist yet. |

##### 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. |
IfcPropertySetDefinition
| PropertyDefinitionOf | IfcRelDefinesByProperties @RelatingPropertyDefinition | S[0:1] | Reference to the relation to one or many objects that are characterized by the property definition. The reference may be omitted, if the property definition is used to define a style library and no instances, to which the particular style of property set is associated, exist yet. |

##### Formal representations

XSD Specification
`<xs:element name="IfcPropertySetDefinition" type="ifc:IfcPropertySetDefinition" abstract="true" substitutionGroup="ifc:IfcPropertyDefinition" nillable="true"/>
<xs:complexType name="IfcPropertySetDefinition" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:IfcPropertyDefinition"/>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcPropertySetDefinition
ABSTRACT SUPERTYPE OF(ONEOF(IfcElementQuantity, IfcPropertySet))
SUBTYPE OF (IfcPropertyDefinition);
INVERSE
PropertyDefinitionOf : SET [0:1] OF IfcRelDefinesByProperties FOR RelatingPropertyDefinition;
END_ENTITY;

EXPRESS-G diagram

`

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