Relation dl#depends_on__dependson (endurant,quality_or_endurant_or_perdurant)
  subtype:  physically_depends_on  descriptively_depends_on
  inverse:  depend_on_of
  supertype:  mediated_relation (entity,entity)
     supertype:  conceptual_relation (entity,entity)
        supertype:  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:  relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type