IfcRelationship

Semantic definitions at the entity

Entity definition

IfcRelationship is the abstract generalization of all objectified relationships in IFC. Objectified relationships are the preferred way to handle relationships among objects. This allows to keep relationship specific properties directly at the relationship and opens the possibility to later handle relationship specific behavior.

There are two different types of relationships, 1-to-1 relationships and 1-to-many relationship. used within the subtypes of IfcRelationship. The following convention applies to all subtypes:

The two sides of the objectified relationship are named
Relating+<name of relating object> and
Related+<name of related object>
In case of the 1-to-many relationship, the related side of the relationship shall be an aggregate being a set 1:N

HISTORY New entity in IFC1.0.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	G
IfcRoot
1	GlobalId	IfcGloballyUniqueId		Assignment of a globally unique identifier within the entire software world.	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
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
4	Description	IfcText	?	Optional description, provided for exchanging informative comments.	X
IfcRelationship

Definitions applying to General Usage

Concept inheritance

#	Concept	Template	Model View
IfcRoot
	Identity	Software Identity	General Usage
	Revision Control	Revision Control	General Usage

Formal representations

XML Specification

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

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

  <xs:complexContent>

   <xs:extension base="ifc:IfcRoot"/>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcRelationship

 ABSTRACT SUPERTYPE OF(ONEOF(IfcRelAssigns, IfcRelAssociates, IfcRelConnects, IfcRelDeclares, IfcRelDecomposes, IfcRelDefines))

 SUBTYPE OF (IfcRoot);

END_ENTITY;

 EXPRESS-G diagram

	Objektifizierte Relation (allgemein)
	Relationship
	Relation