Only classes were introduced in the CRM that are domains or ranges for the relevant relationships, such that any other ontological refinement of the classes can be done as additional “terminological distinction” without interfering with the system of relationships.

Such a conceptual model seems to cover the ontological top-level automatically, and provides an integrating framework for the often isolated hierarchies found in terminological systems. We call such a model a “property centric ontology” to stress the specific character and functionality.