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decomposed elements shall have a maximum of 1 level decomposition depth
based on
extended coordination view
05. May 2006
ISG meeting Munich
summary decomposed elements shall have a maximum of 1 level decomposition depth



update 2011-10-07:
This implementer agreement has been withdrawn with immediate effect. The IFC2x3 Coordination View 2.0 compliant applications shall support a decomposition depths of more than one level.

NOTE  In order to avoid potential endless recursions, it is agreed to end import routines after the 9th level of decomposition.

See also agreements #CV-06-119, #CV-06-120


Outdated agreement

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:

  • The parts contained within an element container shall not be containers by themselves. I.e. the decomposition hierarchy shall only have 1 level depth.
    • Example: The roof slabs in the roof example above shall not be aggregated into rafters and claddings (as this would be a 2 level deep decomposition