SBVR11 — SBVR Issue: can a role range over multiple object types

The fact type "role ranges over object type " appears in section 8.1.1. As defined – due to the "open world" aspect of SBVR – it appears that a role can range over multiple object types, which does not make much sense. But if you look at the MeaningAndRepresentation-model.xml file, you will find confirmation that a role can range over multiple object types.

This has a downstream impact in the MDT-SBVR open source Eclipse project, where the .xml file is converted directly to an EMF model and a matching Java implementation. The API for setting an instance of this fact type permits each role to range over multiple object types. This has two impacts: (a) adds complexity to the API; (b) forces tool vendors to try to figure out the semantics of one role that ranges over multiple object types.

Either the specification should explain what it means for a role to range over multiple object types, or it should introduce a Necessity: "each role ranges over exactly one object type".

Add a clarifying note to the entry for ‘role ranges over object type’.