IFC4 properties NOT in this set (e.g. Reference, LoadBearing, ExtendToStructure)
must be omitted from IFC5 export — the viewer reports "Missing schema" errors for them.
Name and Description are handled separately (always exported), so they're excluded here.
Property names that have official IFC5 schema definitions in prop@v5a.ifcx. Source: https://github.com/buildingSMART/ifcx.dev/blob/main/@standards.buildingsmart.org/ifc/core/prop@v5a.ifcx
IFC4 properties NOT in this set (e.g. Reference, LoadBearing, ExtendToStructure) must be omitted from IFC5 export — the viewer reports "Missing schema" errors for them.
Name and Description are handled separately (always exported), so they're excluded here.