A concept is often used as a mutually exclusive, fundamental, identity-bearing kind for its members. But there are also other concepts where members can come and go over time without changing their essences. This profile calls this sort of concept a “Facet”. A particular thing can be a member of any number of facets at any time.

This version of the concept modeling profile specification defines only two kinds of facets, but may define more in subsequent versions. The defined facets are currently «Role» and «Phase». They are described in the following subsections, linked in the Related pages section below.