Relation pm#how_much_relation (*)
  subtype:  pm#duration  pm#relation_to_attribute_or_quality_or_measure  pm#relation_from_collection_to_number
  supertype:  pm#how_relation__howrelation (*)
     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 
        >part of:  pm#relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type