Relation pm#object_subdomain__subdomain_of_object (pm#thing_that_is_not_a_domain,pm#domain)
  inverse:  pm#core_domain_object
  supertype:  pm#relation_from_a_thing_that_is_not_a_domain__thing_in_domain_of_object (pm#thing_that_is_not_a_domain,?)
     supertype:  pm#domain_related_relation__domain-related-thing (?,?)
        supertype:  pm#relation_playing_a_special_role (*)  this type permits to categorize relations according to their roles ; this is a traditional but quite subjective way of categorizing relations
           >part of:  pm#relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type