BuildingSMART Proposed Recommendation: EXPRESS-to-OWL conversion routine

In this Technical Report, the BuildingSMART Linked Data Working Group (LDWG) documents the EXPRESS-to-OWL conversion routine that it proposes to the standardisation committee of BuildingSMART. This conversion routine is independent of any practical implementation in software. It lists the ways in which the diverse data types in EXPRESS can be uniformly converted into OWL concepts. When implementing this conversion routine, an OWL ontology can be obtained from the IFC schema (tested on IFC2X3_TC1, IFC2X3_Final, IFC4, IFC4_ADD1).