IfcRelAssigns

Semantic definitions at the entity

Entity definition

The assignment relationship, IfcRelAssigns, is a generalization of "link" relationships among instances of IfcObject and its various 1^st level subtypes. A link denotes the specific association through which one object (the client) applies the services of other objects (the suppliers), or through which one object may navigate to other objects.

The client is denoted as the relating object and is established at the level of the specific, instantiable subtypes of IfcRelAssigns. The suppliers are denoted as the related objects and they are established by the RelatedObjects attribute.

NOTE The terms "client" and "supplier" are used in a general concept and do not imply any meaning for implementations of systems (like client-server).

EXAMPLE A resource may receive information about its nature of representing real building products by establishing a link between IfcResource and IfcBuildingElement (subtype of IfcProduct) through the assignment relationship IfcRelAssignsToResource. The resource is then the client that applies the services of other objects (here building elements) to express the particular view of elements to be consumed as a resource in a process.

The assignment relationship establishs a bi-directional relationship among the participating objects and does not imply any dependency. The subtypes of IfcRelAssigns establishes the particular semantic meaning of the assignment relationship.

HISTORY New entity in IFC2x.

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
5	RelatedObjects	IfcObjectDefinition	S[1:?]	Related objects, which are assigned to a single object. The type of the single (or relating) object is defined in the subtypes of IfcRelAssigns.	X
6	RelatedObjectsType	IfcObjectTypeEnum	[0:1]	Particular type of the assignment relationship. It can constrain the applicable object types, used within the role of RelatedObjects.	X

Formal Propositions

Rule	Description
WR1	Rule checks whether the types of the assigned related objects comply with the contraint given by the RelatedObjectsType. The rule is important for constraint checks at subtypes of IfcRelAssigns or at subtypes of IfcObject, which refers to assignment relationships through the inverse HasAssignments relation.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcRoot
1	GlobalId	IfcGloballyUniqueId	[1:1]	Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	[0:1]	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.	X
3	Name	IfcLabel	[0:1]	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
4	Description	IfcText	[0:1]	Optional description, provided for exchanging informative comments.	X
IfcRelationship
IfcRelAssigns
5	RelatedObjects	IfcObjectDefinition	S[1:?]	Related objects, which are assigned to a single object. The type of the single (or relating) object is defined in the subtypes of IfcRelAssigns.	X
6	RelatedObjectsType	IfcObjectTypeEnum	[0:1]	Particular type of the assignment relationship. It can constrain the applicable object types, used within the role of RelatedObjects.	X

Definitions applying to Common Use Definitions

Concept inheritance

#	Concept	Model View
IfcRoot
	Software Identity	Common Use Definitions
	Revision Control	Common Use Definitions

Formal representations

XSD Specification

 <xs:element name="IfcRelAssigns" type="ifc:IfcRelAssigns" abstract="true" substitutionGroup="ifc:IfcRelationship" nillable="true"/>

 <xs:complexType name="IfcRelAssigns" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:IfcRelationship">

    <xs:sequence>

     <xs:element name="RelatedObjects">

      <xs:complexType>

       <xs:sequence>

        <xs:element ref="ifc:IfcObjectDefinition" maxOccurs="unbounded"/>

       </xs:sequence>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcObjectDefinition"/>

       <xs:attribute ref="ifc:cType" fixed="set"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

    </xs:sequence>

    <xs:attribute name="RelatedObjectsType" type="ifc:IfcObjectTypeEnum" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcRelAssigns

 ABSTRACT SUPERTYPE OF(ONEOF(IfcRelAssignsToActor, IfcRelAssignsToControl, IfcRelAssignsToGroup, IfcRelAssignsToProcess, IfcRelAssignsToProduct, IfcRelAssignsToResource))

 SUBTYPE OF (IfcRelationship);

  RelatedObjects : SET [1:?] OF IfcObjectDefinition;

  RelatedObjectsType : OPTIONAL IfcObjectTypeEnum;

 WHERE

  WR1 : IfcCorrectObjectAssignment(RelatedObjectsType, RelatedObjects);
END_ENTITY;

 EXPRESS-G diagram

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