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#CV-2x3-120

material information for decomposed elements shall only be given at the element part level
number
#CV-06-120
based on
IFC2x3
effects
extended coordination view
date
05. May 2006
initiator
ISG meeting Munich
summary material information for decomposed elements shall only be given at the element part level

 

Description

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 is a container, then the material information (IfcRelAssociatesMaterial --> IfcMaterial|IfcMaterialLayerSet|IfcMaterialLayerSetUsage) shall only be assigned to the parts, not to the container

 

update [06-07-2011]
agreement for the IFC2x3 Coordination View V2.0

The material information may either be provided at the decomposed parts of the element container, or to the type of that part. Taking the example from above:

  • If the building element is a container, then the material information shall either be assigned to the parts, here IfcSlab, or to the type of the part, here IfcSlabType referenced by IfcSlab <-- IfcRelDefinesByType --> IfcSlabType.

 

see also agreement #CV-06-119, #CV-06-121