Relation pm#why_relation__whyrelation (*)
  supertype:  pm#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 
  subtype:  pm#cause (pm#situation,pm#situation)  see also rst#cause
     subtype:  sumo#causes (sumo#process,sumo#process)  the process in the 1st argument brings about the process in the 2nd argument
  subtype:  pm#consequence (pm#situation,pm#situation)  see also rst#effect
  subtype:  pm#method (pm#process,pm#description)
  subtype:  pm#goal (pm#process,pm#situation)
  subtype:  pm#triggering_event (pm#process,pm#event)
  subtype:  pm#ending_event (pm#process,pm#event)
  subtype:  pm#precondition (pm#process,pm#situation)
  subtype:  pm#postcondition (pm#process,pm#situation)
  subtype:  pm#purpose (?,?)
     subtype:  pm#goal (pm#process,pm#situation)
     subtype:  rst#purpose (pm#description_content/medium/container,pm#description_content/medium/container)  situation that the described action is intended to reach