Relation pm#agent__doer (situation [48..*],entity [49..*])
  subtype:  organizer  participant {seller customer}  responsible_agent  agent
  supertype:  doer/object/result (situation,?)
     supertype:  doer/object/result/place (situation,?)
        supertype:  case_relation__thematic_relation (situation,*)
           supertype:  relation_from_situation (situation,*)
              supertype:  relation_from/to_thing_of_common_kind (*)  this type permits to categorize relations according to their signatures and hence offers (i) a concise way to set essential exclusion relations, and (ii) a systematic and easy-to-follow categorization
                 >part of:  relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
  supertype:  who_relation__whorelation (*)
     supertype:  wh-/how_relation (*)  this type permits to categorize relations according to the usual who/what/why/where/when/how questions ; this is a traditional but very subjective and ineffective 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