A Possession of property is a Specialisation_of_class that is between a Class_of_physical_individual and an Independent_property_definition.
EXPRESS specification:
*) ENTITY Possession_of_property SUBTYPE OF (Specialisation_of_class); subclass : Class_of_physical_individual; superclass : Independent_property_definition; END_ENTITY; (*
Attribute definitions:
subclass: the Class_of_physical_individual that has each of its members within the superclass.
superclass: the Independent_property_definition that contains each member of the subclass.