A Membership_of_property_space is a Classification that is between anIndpendent_property_definition and a Property_space and that indicates the Indpendent_property_definition is a member of the Property_space.
EXPRESS specification:
*) ENTITY Membership_of_property_space SUBTYPE OF (Classification); class : Property_space; member : Independent_property_definition; END_ENTITY; (*
Attribute definitions:
class: the Property_space that has the member.
member: the Indpendent_property_definition that is a member of the class.