#### 5.1.3.12 IfcPropertySetDefinition

| Définition d'ensemble de propriété
| Definition der Merkmalliste (allgemein)

IfcPropertySetDefinition is a generalization of all individual property sets that can be assigned to an object or type object. The property set definition can be either:

> Dynamically extendable property sets - IfcPropertySet, a set of 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. Dynamically defined property sets may have an underlying template provided by IfcPropertySetTemplate.

> Statically defined property sets - IfcPreDefinedPropertySet, a property set entity that exists within the IFC specification. The semantic meaning of each statically defined property set is declared by its entity type and the meaning of the properties is defined by the name and data type of the explicit attribute representing it.

> HISTORY New entity in IFC2x

> IFC4 CHANGE The subtype IfcPreDefinedPropertySet has been added.

Relationship use definition

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

- Assignment to object types - an DefinesType direct relationship to IfcTypeObject that applies the property set, with all included properties, to the object type. Those properties apply to all object occurrences having the same object type.
- Assignment to object occurrences - an DefinesOccurrence relationship to IfcRelDefinesByProperties that applies the property set, with all included properties, to the object occurrence.

> NOTE Properties assigned to object occurrences may override properties assigned to the object type. See IfcRelDefinesByType for further information.

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(IfcPropertySet, IfcQuantitySet))

| SUBTYPE OF (IfcPropertyDefinition);

| INVERSE

DefinesType | : | SET OF IfcTypeObject FOR HasPropertySets;
DefinesOccurrence | : | SET [0:1] OF IfcRelDefinesByProperties FOR RelatingPropertyDefinition;

END_ENTITY;

Attribute Definitions:

DefinesType | : | The type object to which the property set is assigned. The property set acts as a shared property set to all occurrences of the type object. NOTE The relationship between the IfcPropertySetDefinition and the IfcTypeObject is a direct relationship, not utilizing IfcRelDefinesByProperties, for maintaining compatibility with earlier releases of this standard. IFC4 CHANGE The cardinality has been changed from 0:1 to 0:? with upward compatibility for file based exchange.
DefinesOccurrence | : | Reference to the relation to one or many object occurrences that are characterized by the property set definition. A single property set can be assigned to multiple object occurrences using the objectified relationship IfcRefDefinesByProperties. IFC4 CHANGE Inverse attribute renamed from PropertyDefinitionOf with upward compatibility for file-based exchange.

Inheritance Graph:

ENTITY IfcPropertySetDefinition

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcPropertyDefinition

| INVERSE

HasContext | : | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
HasAssociations | : | SET OF IfcRelAssociates FOR RelatedObjects;

| ENTITY IfcPropertySetDefinition

| INVERSE

DefinesType | : | SET OF IfcTypeObject FOR HasPropertySets;
DefinesOccurrence | : | SET [0:1] OF IfcRelDefinesByProperties FOR RelatingPropertyDefinition;

END_ENTITY;

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