Relation pm#constitution (?,?)
  supertype:  pm#partial_ordering_relation  this category only serves structuration purposes: it is instance of pm#partial_ordering_relation_type which is not instance of pm#class_of_inheritable_relation_type
  instance of:  pm#partial_ordering_relation_type
  subtype:  pm#substance (? -> ?)
     subtype:  pm#matter (pm#physical_entity -> pm#physical_entity_part_or_substance)
  subtype:  dl#constituted_by__constitutedby__substance___K__k (dl#entity,dl#entity)
     subtype:  dl#has_member__hasmember (dl#entity,dl#entity)