Relation pm#xor__either (pm#description,pm#description)
  supertype:  pm#contextualizing_logical_relation__contextualizinglogicalrelation (pm#description,pm#description)
     supertype:  pm#logical_relation__logicalrelation (pm#description,pm#description)
        supertype:  pm#relation_from_description (pm#description,*)
           supertype:  pm#relation_from_description_content/medium/container (pm#description_content/medium/container,*)
              supertype:  pm#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:  pm#relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type
     supertype:  pm#contextualizing_relation__contextualizingrelation (pm#description,*)
        supertype:  pm#relation_from_description (pm#description,*)
        supertype:  pm#what_relation (*)
           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