IFC Syntax : Classifications

An IFC model links its objects to external classification systems (Uniclass, OmniClass, MasterFormat, ETIM) and to external libraries through a small, fixed set of entities. This skill covers those entities, the attribute that carries the actual code, and the IFC2x3 / IFC4 / IFC4.3 version differences that break round-tripped files.

Applies to IFC2x3, IFC4, and IFC4.3. Several attribute names and types changed across versions : see the Version Differences section.