IFC 4.3.1.0 (IFC4X3_ADD1)

5.1.3.24 IfcRelAssignsToGroup

5.1.3.24.1 Semantic 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.

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.

5.1.3.24.2 Entity inheritance

5.1.3.24.3 Attributes

# Attribute Type Description
IfcRoot (4)
1 GlobalId IfcGloballyUniqueId

Assignment of a globally unique identifier within the entire software world.

2 OwnerHistory OPTIONAL 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,

3 Name OPTIONAL 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.

4 Description OPTIONAL IfcText

Optional description, provided for exchanging informative comments.

IfcRelAssigns (2)
5 RelatedObjects SET [1:?] OF IfcObjectDefinition

Related objects, which are assigned to a single object. The type of the single (or relating) object is defined in the subtypes of IfcRelAssigns.

6 RelatedObjectsType OPTIONAL IfcStrippedOptional

Particular type of the assignment relationship. It can constrain the applicable object types, used within the role of RelatedObjects.

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IfcRelAssignsToGroup (1)
7 RelatingGroup IfcGroup

Reference to group that contains all assigned group members.

Table 5.1.3.24.A

5.1.3.24.4 Formal propositions

Name Description
NoSelfReference

The instance to with the relation points shall not be contained in the set of RelatedObjects.

SIZEOF(QUERY(Temp <* SELF\IfcRelAssigns.RelatedObjects | RelatingGroup :=: Temp)) = 0
Table 5.1.3.24.B

5.1.3.24.5 Concept usage

Concept Usage Description
IfcRoot (2)
Revision Control General

Ownership, history, and merge state is captured using IfcOwnerHistory.

Software Identity General

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

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Table 5.1.3.24.C

5.1.3.24.6 Formal representation

ENTITY IfcRelAssignsToGroup
 SUPERTYPE OF (ONEOF
	(IfcRelAssignsToGroupByFactor))
 SUBTYPE OF (IfcRelAssigns);
	RelatingGroup : IfcGroup;
 WHERE
	NoSelfReference : SIZEOF(QUERY(Temp <* SELF\IfcRelAssigns.RelatedObjects | RelatingGroup :=: Temp)) = 0;
END_ENTITY;

5.1.3.24.7 References

5.1.3.24.8 Changelog

5.1.3.24.8.1 IFC4

  • where rule, NoSelfReference
  • where rule, WR1