IfcRelDefinesByProperties

BACnet MVD

#### IfcRelDefinesByProperties

Natural language names

| Definiert durch Merkmale - Relation
| Rel Defines By Properties
| Définition par propriétés

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcRelDefinesByProperties |  |  |  |
OwnerHistory |  |  | MODIFIED | Instantiation changed to OPTIONAL.
RelatedObjects | X | X | MODIFIED | Type changed from IfcObject to IfcObjectDefinition.
RelatingPropertyDefinition |  |  | MODIFIED | Type changed from IfcPropertySetDefinition to IfcPropertySetDefinitionSelect.

##### Semantic definitions at the entity

Entity definition

The objectified relationship IfcRelDefinesByProperties defines the relationships between property set definitions and objects. Properties are aggregated in property sets. Property sets can be either directly assigned to occurrence objects using this relationship, or assigned to an object type and assigned via that type to occurrence objects. The assignment of an IfcPropertySet to an IfcTypeObject is not handled via this objectified relationship, but through the direct relationship HasPropertySets at IfcTypeObject.

The IfcRelDefinesByProperties is an N-to-N relationship, as it allows for the assignment of one or more property sets to one or more objects. Those objects then share the same property definition.

> HISTORY New entity in IFC2.0. Has been renamed from IfcRelAssignsProperties in IFC2x.

> IFC4 CHANGE The attribute RelatedObjects had been demoted from the supertype IfcRelDefines to IfcRelDefinesByProperties. This relationship has been modified to support multiple property sets referenced by a single relationship.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---

5

RelatedObjects

IfcObjectDefinition

S[1:?]

Reference to the objects (or single object) to which the property definition applies.

> IFC4 CHANGE Data type promoted from subtype IfcObject.

X

6 | RelatingPropertyDefinition | IfcPropertySetDefinitionSelect |  | Reference to the property set definition for that object or set of objects. |  | X

Formal Propositions

Rule | Description
--- | ---

NoRelatedTypeObject

There shall be no related object being of typy IfcTypeObject.

> NOTE The relationship between a IfcTypeObject and a IfcPropertySet is handled through the direct relationship HasPropertySets at IfcTypeObject.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcRoot
1 | GlobalId | IfcGloballyUniqueId |  | Assignment of a globally unique identifier within the entire software world. | X | 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

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 | X
4 | Description | IfcText | ? | Optional description, provided for exchanging informative comments. |  | X
IfcRelationship
IfcRelDefines
IfcRelDefinesByProperties

5

RelatedObjects

IfcObjectDefinition

S[1:?]

Reference to the objects (or single object) to which the property definition applies.

> IFC4 CHANGE Data type promoted from subtype IfcObject.

X

6 | RelatingPropertyDefinition | IfcPropertySetDefinitionSelect |  | Reference to the property set definition for that object or set of objects. |  | X

##### Definitions applying to Design Transfer View

Concept inheritance

# | Concept | Template | Model View
--- | --- | --- | ---
IfcRoot
| Revision Control | Revision Control | Design Transfer View

##### Definitions applying to BACnet View

Concept inheritance

# | Concept | Template | Model View
--- | --- | --- | ---
IfcRoot
| Revision Control | Revision Control | Design Transfer View

##### Examples

- Air terminal element

##### Formal representations

XML Specification
`<xs:element name="IfcRelDefinesByProperties" type="ifc:IfcRelDefinesByProperties" substitutionGroup="ifc:IfcRelDefines" nillable="true"/>
<xs:complexType name="IfcRelDefinesByProperties">
<xs:complexContent>
<xs:extension base="ifc:IfcRelDefines">
<xs:sequence>
<xs:element name="RelatingPropertyDefinition">
<xs:complexType>
<xs:group ref="ifc:IfcPropertySetDefinitionSelect"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcRelDefinesByProperties
SUBTYPE OF (IfcRelDefines);
RelatedObjects : SET [1:?] OF IfcObjectDefinition;
RelatingPropertyDefinition : IfcPropertySetDefinitionSelect;
WHERE
NoRelatedTypeObject : SIZEOF(QUERY(Types <* SELF\IfcRelDefinesByProperties.RelatedObjects | 'IFCKERNEL.IfcTypeObject' IN TYPEOF(Types))) = 0;
END_ENTITY;

EXPRESS-G diagram

`

References: IfcContext IfcObject IfcPropertySetDefinition

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