Natural language names
Weist Gruppe zu - Relation
Rel Assigns To Group
Assignation à groupe
Change log
      OwnerHistoryMODIFIEDInstantiation changed to OPTIONAL.
      RelatedObjectsTypeMODIFIEDStatus changed to Deprecated.
Semantic definitions at the entity
Entity definition

The objectified relationship IfcRelAssignsToGroup handles the assignment of object definitions (individual object occurrences as subtypes of IfcObject, and object types as subtypes of IfcTypeObject) to a group (subtypes of IfcGroup).

The relationship handles the assignment of group members to the group object. It allows for grouping arbitrary objects within a group, including other groups. The grouping relationship can be applied in a recursive manner. The resulting group is of type IfcGroup.

NOTE  Examples of groups include zones as a grouping of spaces, distribution systems as a grouping of building service components, or structural analysis models as a grouping of structural items.

The inherited attribute RelatedObjects gives the references to the objects, which are the elements within the group. The RelatingGroup is the group that comprises all elements. The same object or object type can be included in zero, one or many groups. Grouping relationships are not hierarchical.

Informal Propositions:

  1. The group assignment relationship shall be acyclic, that is, a group shall not participate in its own grouping relationship.
HISTORY  New entity in IFC1.0. It has been renamed from IfcRelGroups in IFC2x.
Attribute definitions
#AttributeTypeCardinalityDescription G
7RelatingGroupIfcGroup Reference to group that contains all assigned group members. X
Formal Propositions
NoSelfReferenceThe instance to with the relation points shall not be contained in the set of RelatedObjects.
Inherited definitions from supertypes
Entity inheritance IfcRelAssignsToGroupByFactor IfcRelAssigns IfcRelationship IfcRoot
Attribute inheritance
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.
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
5RelatedObjectsIfcObjectDefinitionS[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
6RelatedObjectsTypeIfcObjectTypeEnum? Particular type of the assignment relationship. It can constrain the applicable object types, used within the role of RelatedObjects.
IFC4 CHANGE  The attribute is deprecated and shall no longer be used. A NIL value should always be assigned.
7RelatingGroupIfcGroup Reference to group that contains all assigned group members. X
Definitions applying to General Usage

Concept inheritance

#ConceptTemplateModel View
IdentitySoftware IdentityGeneral Usage
Revision ControlRevision ControlGeneral Usage
Formal representations
XML Specification
 <xs:element name="IfcRelAssignsToGroup" type="ifc:IfcRelAssignsToGroup" substitutionGroup="ifc:IfcRelAssigns" nillable="true"/>
 <xs:complexType name="IfcRelAssignsToGroup">
   <xs:extension base="ifc:IfcRelAssigns">
     <xs:element name="RelatingGroup" type="ifc:IfcGroup" nillable="true"/>
EXPRESS Specification
ENTITY IfcRelAssignsToGroup
 SUPERTYPE OF(IfcRelAssignsToGroupByFactor)
 SUBTYPE OF (IfcRelAssigns);
  RelatingGroup : IfcGroup;
  NoSelfReference : SIZEOF(QUERY(Temp <* SELF\IfcRelAssigns.RelatedObjects | RelatingGroup :=: Temp)) = 0;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcGroup

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