Relation pm#relation_from_collection (collection,*)
  exclusion:  relation_from_situation  spatial_relation_from_entity_with_spatial_feature  relation_from_description_content/medium/container  relation_from_attribute_or_quality_or_measure
  subtype:  member  nthrest  relation_from_collection_to_number  list_order_fn  list_length_fn  relation_from_an_ontology  relation_between_collections  relation_from_type
  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:  what_relation (*)
     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