Relation pm#later_situation__latersituation (pm#situation,pm#situation)
  supertype:  pm#relation_from_situation_to_situation  nsm#before
  subtype:  pm#next_situation (pm#situation -> pm#situation)
     subtype:  pm#successor (pm#situation -> pm#situation)
  subtype:  pm#ending_situation__termination (pm#situation -> pm#situation)
  subtype:  pm#postcondition (pm#process,pm#situation)
  subtype:  pm#consequence (pm#situation,pm#situation)  see also rst#effect