In this example, the LicenseTermMetrics only includes four
very common proprietary license types; the named license
type, though most common, is omitted because the relation
between service, customer and agreement in the Head part
of an agreement realises naturally the named license in ontology.
Any user has to belong to a Customer that is actually
a group of users to be able to use a service subscribed
by that Customer. So there is no need to define the named
license and implement it again. At the same time, should
there be a new license type emerging, it is easily accommodated
by adding definition of the new term and including it
in the LicenseTerm definition.