IfcGroup

Natural language names
deGruppe (allgemein)
enGroup
frGroupe
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcGroup
      OwnerHistoryMODIFIEDInstantiation changed to OPTIONAL.
Semantic definitions at the entity
Entity definition

IfcGroup is an generalization of any arbitrary group. A group is a logical collection of objects. It does not have its own position, nor can it hold its own shape representation. Therefore a group is an aggregation under some non-geometrical / topological grouping aspects.

EXAMPLE  An example for a group is a system, since it groups elements under the aspect of their role, regardless of their position in a building. One of the most important usage of a group representing a system is the IfcDistributionSystem, that groups distribution components, such as space heaters and valves into a heating system.

A group can hold any collection of objects, the relationship IfcRelAssignsToGroup is used to establish the group collection. Objects within a group are products, processes, controls, resources, actors or other groups, thus groups can be nested. An object can be part of zero, one, or many groups. Grouping relationships are not required to be hierarchical nor do they imply a dependency.

Groups are assigned to other objects (such as a process or a resource) by the relationship object that refers to the corresponding object:

A group can be exchanged without having already objects within the group collection.

IfcGroup does not define an own object coordinate system, nor does it have an independent shape representation.

NOTE  Use IfcRelAggregates together with the appropriate subtypes of IfcProduct to define an aggregation of products that may have its own position and shape representation. This relationship shall be used to create a product breakdown structure.
HISTORY  New entity in IFC1.0.
IFC4 CHANGE  The inverse IsGroupedBy relationship is set to 0..n
Attribute definitions
#AttributeTypeCardinalityDescription B
IsGroupedByIfcRelAssignsToGroup
@RelatingGroup
S[0:?]Reference to the relationship IfcRelAssignsToGroup that assigns the one to many group members to the IfcGroup object. X
Inherited definitions from supertypes
Entity inheritance IfcStructuralLoadGroup IfcStructuralResultGroup IfcSystem IfcObject IfcObjectDefinition IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionB
IfcRoot
1GlobalIdIfcGloballyUniqueId[1:1] Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory[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
3NameIfcLabel[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
4DescriptionIfcText[0:1] Optional description, provided for exchanging informative comments.X
IfcObjectDefinition
HasAssignmentsIfcRelAssigns
@RelatedObjects
S[0:?]Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.X
NestsIfcRelNests
@RelatedObjects
S[0:1]References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only).
IsNestedByIfcRelNests
@RelatingObject
S[0:?]References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types). X
HasContextIfcRelDeclares
@RelatedDefinitions
S[0:1]References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object.
IsDecomposedByIfcRelAggregates
@RelatingObject
S[0:?]References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts). X
DecomposesIfcRelAggregates
@RelatedObjects
S[0:1]References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only). X
HasAssociationsIfcRelAssociates
@RelatedObjects
S[0:?]Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification.X
IfcObject
5ObjectType- This attribute is out of scope for this model view definition and shall not be set.
IsTypedByIfcRelDefinesByType
@RelatedObjects
S[0:1]Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type. X
IsDefinedByIfcRelDefinesByProperties
@RelatedObjects
S[0:?]Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object. X
IfcGroup
IsGroupedByIfcRelAssignsToGroup
@RelatingGroup
S[0:?]Reference to the relationship IfcRelAssignsToGroup that assigns the one to many group members to the IfcGroup object. X
Definitions applying to Bridge View

Concept inheritance

#ConceptModel View
IfcRoot
Software IdentityBridge View
User IdentityBridge View
Object OwnershipBridge View
IfcObject
Property Sets for ObjectsBridge View
Formal representations
XSD Specification
 <xs:element name="IfcGroup" type="ifc:IfcGroup" substitutionGroup="ifc:IfcObject" nillable="true"/>
 <xs:complexType name="IfcGroup">
  <xs:complexContent>
   <xs:extension base="ifc:IfcObject"/>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcGroup
 SUPERTYPE OF(ONEOF(IfcStructuralLoadGroup, IfcStructuralResultGroup, IfcSystem))
 SUBTYPE OF (IfcObject);
 INVERSE
  IsGroupedBy : SET OF IfcRelAssignsToGroup FOR RelatingGroup;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

Link to this page  Link to this page