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geometry for decomposed elements shall be either at the element container or at the element part level
based on
IFC2x2, IFC2x3
extended coordination view
05. May 2006
ISG meeting Munich
summary geometry for decomposed elements shall either be given at the element container or at the element part level



The IFC specification allows all subtypes of IfcBuildingElement (and other) to act as a container entity, i.e. to be a decomposed element having parts. This is expressed by an IfcRelAggregates relationship entity pointing to the container with RelatingObject and it referenced by the inverse attribute IsDecomposedBy. An example is a roof, containing two roof slabs:

  • IfcRoof <--RelatingObject-- IfcRelAggregates --RelatedObjects--> IfcSlab (PredefinedType=.ROOF.)

The following agreement is made:

  • If the building element acts as a container, i.e. has parts associated, and those parts have own shape representations, then the container shall have no shape representation.


addition 2011-03-10

initiator: Coordination View V2.0 model view definition development

The requirement only concerns the shape representation of the container with RepresentationIdentifier = "Body". The container may have an own shape representation (e.g. of RepresentationIdentifier = "Axis" or "Box") even if the parts have the shape representation with RepresentationIdentifier = "Body".



Figure: correct assignment of 'Body' shape representation to parts only


see also agreement #CV-06-120, #CV-06-121