IfcRelDefinesByObject

Natural language names
Definiert durch Objekte - Relation
Rel Defines By Object
Définition par objet
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4 4.0.0.0
    IfcRelDefinesByObjectADDED
IFC4 Addendum 2 4.0.2.0
    IfcRelDefinesByObject
      RelatingObjectXMODIFIEDXsdformat changed from Attribute to Hidden.
IFC2x3 to IFC4 4.0.0.0
    IfcRelDefinesByObjectADDED
IFC4 Addendum 2 4.0.2.0
    IfcRelDefinesByObject
      RelatingObjectXMODIFIEDXsdformat changed from Attribute to Hidden.
Semantic definitions at the entity
Entity definition

The objectified relationship IfcRelDefinesByObject defines the relationship between an object taking part in an object type decomposition and an object occurrences taking part in an occurrence decomposition of that type.

The IfcRelDefinesByObject is a 1-to-N relationship, as it allows for the assignment of one declaring object information to a single or to many reflected objects. Those objects then share the same object property sets and, for subtypes of IfcProduct, the eventually assigned representation maps.

Only objects that take part in a type decomposition and in an occurrence decomposition of the same type can be connected by the IfcRelDefinesByObject relationship. The IfcRelDefinesByObject links the decomposed object type part, also called the "declaring part" with the occurrence of that part inside the occurrence of the decomposed type, also called the "reflected part", as shown in Figure 135.

 

"instance diagram"

Figure 135 — Part definition relationships

The IfcRelDefinesByObject can be used together with the shape representations of the product type as shown in Figure 136. The IfcShapeRepresentation of the "declaring part" is referenced by the "reflected part". The IfcObjectPlacement of the model occurrence (the whole) determines the position within the project context.

"geometry diagram"

Figure 136 — Part definition relationships with shape representation

HISTORY  New entity in IFC4.

Attribute definitions
#AttributeTypeCardinalityDescription G
5RelatedObjectsIfcObjectS[1:?] Objects being part of an object occurrence decomposition, acting as the "reflecting parts" in the relationship. X
6RelatingObjectIfcObject Object being part of an object type decomposition, acting as the "declaring part" in the relationship. X
Inherited definitions from supertypes
Entity inheritance IfcRelDefines IfcRelationship IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRoot
1GlobalIdIfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory? 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
3NameIfcLabel? 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
4DescriptionIfcText? Optional description, provided for exchanging informative comments. X
IfcRelationship
IfcRelDefines
IfcRelDefinesByObject
5RelatedObjectsIfcObjectS[1:?] Objects being part of an object occurrence decomposition, acting as the "reflecting parts" in the relationship. X
6RelatingObjectIfcObject Object being part of an object type decomposition, acting as the "declaring part" in the relationship. X
Definitions applying to General Usage

Concept inheritance

#ConceptTemplateModel View
IfcRoot
IdentitySoftware IdentityGeneral Usage
Revision ControlRevision ControlGeneral Usage
Formal representations
XML Specification
 <xs:element name="IfcRelDefinesByObject" type="ifc:IfcRelDefinesByObject" substitutionGroup="ifc:IfcRelDefines" nillable="true"/>
 <xs:complexType name="IfcRelDefinesByObject">
  <xs:complexContent>
   <xs:extension base="ifc:IfcRelDefines">
    <xs:sequence>
     <xs:element name="RelatedObjects">
      <xs:complexType>
       <xs:sequence>
        <xs:element ref="ifc:IfcObject" maxOccurs="unbounded"/>
       </xs:sequence>
       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcObject"/>
       <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 IfcRelDefinesByObject
 SUBTYPE OF (IfcRelDefines);
  RelatedObjects : SET [1:?] OF IfcObject;
  RelatingObject : IfcObject;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcObject

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