#### 5.1.3.17 IfcRelAssignsToGroup

| Assignation à groupe
| Weist Gruppe zu - Relation

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.

XSD Specification:

<xs:element name="IfcRelAssignsToGroup" type="ifc:IfcRelAssignsToGroup" substitutionGroup="ifc:IfcRelAssigns" nillable="true"/>
<xs:complexType name="IfcRelAssignsToGroup">
<xs:complexContent>
<xs:extension base="ifc:IfcRelAssigns">
<xs:sequence>
<xs:element name="RelatingGroup" type="ifc:IfcGroup" nillable="true"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcRelAssignsToGroup

| SUBTYPE OF (IfcRelAssigns);

RelatingGroup | : | IfcGroup;

| WHERE

NoSelfReference | : | SIZEOF(QUERY(Temp <* SELF\IfcRelAssigns.RelatedObjects | RelatingGroup :=: Temp)) = 0;

END_ENTITY;

Attribute Definitions:

RelatingGroup | : | Reference to group that contains all assigned group members.

Formal Propositions:

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

Inheritance Graph:

ENTITY IfcRelAssignsToGroup

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcRelationship

| ENTITY IfcRelAssigns

RelatedObjects | : | SET [1:?] OF IfcObjectDefinition;
RelatedObjectsType | : | OPTIONAL IfcStrippedOptional;

| ENTITY IfcRelAssignsToGroup

RelatingGroup | : | IfcGroup;

END_ENTITY;

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