IfcReference

Natural language names
Bezug
Reference
R茅f茅rence
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcReferenceADDED
IFC4 Addendum 1
    IfcReference
      ListPositionsMODIFIEDType changed from INTEGER to IfcInteger.
Semantic definitions at the entity
Entity definition

This entity is used to refer to a value of an attribute on an instance. It may refer to the value of a scalar attribute or a value within a collection-based attribute. Referenced attributes may be direct values, object references, collections, inverse object references, and inverse collections. References may be chained to form a path of object-attribute references.

Attribute definitions
#AttributeTypeCardinalityDescription G
1TypeIdentifierIfcIdentifier? Optional identifier of the entity or type such as 'IfcMaterialLayerSet'. For entity, type, or select-based references within a collection, this resolves the reference to such type. If omitted, the type is assumed to be the same as the declared referencing attribute.
EXAMPLE  IfcRelAssociatesMaterial.RelatingMaterial may be resolved to IfcMaterialLayerSet.
X
2AttributeIdentifierIfcIdentifier? Optionally identifies a direct or inverse attribute within an entity such as 'MaterialLayers'. If TypeIdentifier is specified and refers to an entity, the attribute must exist within the referenced entity. A null value indicates a reference to the type or entity itself, such as for indicating that the type of a value must match a specified constraint. X
3InstanceNameIfcLabel? Optionally identifies an instance within a collection according to name. If the instance has an attribute called 'Name', such attribute is used for comparison; otherwise the first STRING-based attribute of the entity is used.
EXAMPLE  IfcRoot-based entities such as IfcPropertySet use the Name attribute; IfcRepresentation entities use the RepresentationIdentifier attribute.
X
4ListPositionsIfcInteger? L[1:?] Optionally identifies an instance within a collection according to position starting at 1. For referencing single-level collections, this attribute contains a single member; for referencing multi-level collections, then this LIST attribute contains multiple members starting from the outer-most index.X
5InnerReferenceIfcReference? Optional reference to an inner value for ENTITY, SELECT, SET, or LIST attributes. A path may be formed by linking IfcReference instances together.
EXAMPLE  A material layer thickness may be referenced using several instances: #1=IFCREFERENCE($,'IfcSlab','HasAssociations',#2); #2=IFCREFERENCE($,'IfcMaterialLayerSet','MaterialLayers',#3); #3=IFCREFERENCE('Core','IfcMaterialLayer','LayerThickness',$);
X
Inherited definitions from supertypes
Entity inheritance
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcReference
1TypeIdentifierIfcIdentifier? Optional identifier of the entity or type such as 'IfcMaterialLayerSet'. For entity, type, or select-based references within a collection, this resolves the reference to such type. If omitted, the type is assumed to be the same as the declared referencing attribute.
EXAMPLE  IfcRelAssociatesMaterial.RelatingMaterial may be resolved to IfcMaterialLayerSet.
X
2AttributeIdentifierIfcIdentifier? Optionally identifies a direct or inverse attribute within an entity such as 'MaterialLayers'. If TypeIdentifier is specified and refers to an entity, the attribute must exist within the referenced entity. A null value indicates a reference to the type or entity itself, such as for indicating that the type of a value must match a specified constraint. X
3InstanceNameIfcLabel? Optionally identifies an instance within a collection according to name. If the instance has an attribute called 'Name', such attribute is used for comparison; otherwise the first STRING-based attribute of the entity is used.
EXAMPLE  IfcRoot-based entities such as IfcPropertySet use the Name attribute; IfcRepresentation entities use the RepresentationIdentifier attribute.
X
4ListPositionsIfcInteger? L[1:?] Optionally identifies an instance within a collection according to position starting at 1. For referencing single-level collections, this attribute contains a single member; for referencing multi-level collections, then this LIST attribute contains multiple members starting from the outer-most index.X
5InnerReferenceIfcReference? Optional reference to an inner value for ENTITY, SELECT, SET, or LIST attributes. A path may be formed by linking IfcReference instances together.
EXAMPLE  A material layer thickness may be referenced using several instances: #1=IFCREFERENCE($,'IfcSlab','HasAssociations',#2); #2=IFCREFERENCE($,'IfcMaterialLayerSet','MaterialLayers',#3); #3=IFCREFERENCE('Core','IfcMaterialLayer','LayerThickness',$);
X
Formal representations
XML Specification
 <xs:element name="IfcReference" type="ifc:IfcReference" substitutionGroup="ifc:Entity" nillable="true"/>
 <xs:complexType name="IfcReference">
  <xs:complexContent>
   <xs:extension base="ifc:Entity">
    <xs:sequence>
     <xs:element name="InnerReference" type="ifc:IfcReference" nillable="true" minOccurs="0"/>
    </xs:sequence>
    <xs:attribute name="TypeIdentifier" type="ifc:IfcIdentifier" use="optional"/>
    <xs:attribute name="AttributeIdentifier" type="ifc:IfcIdentifier" use="optional"/>
    <xs:attribute name="InstanceName" type="ifc:IfcLabel" use="optional"/>
    <xs:attribute name="ListPositions" use="optional">
     <xs:simpleType>
      <xs:restriction>
       <xs:simpleType>
        <xs:list itemType="ifc:IfcInteger"/>
       </xs:simpleType>
      </xs:restriction>
     </xs:simpleType>
    </xs:attribute>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcReference;
  TypeIdentifier : OPTIONAL IfcIdentifier;
  AttributeIdentifier : OPTIONAL IfcIdentifier;
  InstanceName : OPTIONAL IfcLabel;
  ListPositions : OPTIONAL LIST [1:?] OF IfcInteger;
  InnerReference : OPTIONAL IfcReference;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcMetric IfcReference IfcMetricValueSelect IfcAppliedValueSelect IfcTableColumn

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