IfcExternalReferenceRelationship

BACnet MVD

#### IfcExternalReferenceRelationship

Natural language names

| Externer Bezug - Relation
| External Reference Relationship

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcExternalReferenceRelationship |  |  | ADDED |

##### Semantic definitions at the entity

Entity definition

IfcExternalReferenceRelationship is a relationship entity that enables objects from the IfcResourceObjectSelect to have the ability to be tagged by external references.

> NOTE This relationship is used to assign classification, library or document information to entities that do not inherit from IfcRoot. It has a similar functionality as the subtypes of IfcRelAssociates.

> HISTORY New entity in IFC4.

Attribute definitions

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

3

RelatingReference

IfcExternalReference

An external reference that can be used to tag an object within the range of IfcResourceObjectSelect.

> NOTE External references can be a library reference (for example a dictionary or a catalogue reference), a classification reference, or a documentation reference.

X

4 | RelatedResourceObjects | IfcResourceObjectSelect | S[1:?] | Objects within the list of IfcResourceObjectSelect that can be tagged by an external reference to a dictionary, library, catalogue, classification or documentation. |  | X

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcResourceLevelRelationship
1 | Name | IfcLabel | ? | A name used to identify or qualify the relationship. |  | X
2 | Description | IfcText | ? | A description that may apply additional information about the relationship. |  | X
IfcExternalReferenceRelationship

3

RelatingReference

IfcExternalReference

An external reference that can be used to tag an object within the range of IfcResourceObjectSelect.

> NOTE External references can be a library reference (for example a dictionary or a catalogue reference), a classification reference, or a documentation reference.

X

4 | RelatedResourceObjects | IfcResourceObjectSelect | S[1:?] | Objects within the list of IfcResourceObjectSelect that can be tagged by an external reference to a dictionary, library, catalogue, classification or documentation. |  | X

##### Formal representations

XML Specification
`<xs:element name="IfcExternalReferenceRelationship" type="ifc:IfcExternalReferenceRelationship" substitutionGroup="ifc:IfcResourceLevelRelationship" nillable="true"/>
<xs:complexType name="IfcExternalReferenceRelationship">
<xs:complexContent>
<xs:extension base="ifc:IfcResourceLevelRelationship">
<xs:sequence>
<xs:element name="RelatingReference" type="ifc:IfcExternalReference" nillable="true"/>
<xs:element name="RelatedResourceObjects">
<xs:complexType>
<xs:group ref="ifc:IfcResourceObjectSelect" maxOccurs="unbounded"/>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcResourceObjectSelect"/>
<xs:attribute ref="ifc:cType" fixed="set"/>
<xs:attribute ref="ifc:arraySize" use="optional"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcExternalReferenceRelationship
SUBTYPE OF (IfcResourceLevelRelationship);
RelatingReference : IfcExternalReference;
RelatedResourceObjects : SET [1:?] OF IfcResourceObjectSelect;
END_ENTITY;

EXPRESS-G diagram

`

References: IfcActorRole IfcApproval IfcConstraint IfcAppliedValue IfcTimeSeries IfcExternalReference IfcMaterialDefinition IfcContextDependentUnit IfcConversionBasedUnit IfcProfileDef IfcPropertyAbstraction IfcPhysicalQuantity

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