Relation sumo#synonymous_external_concept (pm#string,?,sumo#language)  the 2nd argument has the same meaning as the 1st in the language denoted by the 3rd argument
  exclusion:  sumo#subsumed_external_concept  sumo#subsuming_external_concept
  supertype:  sumo#related_external_concept (pm#string,?,sumo#language)  used to signify a three-place relation between a concept in an external knowledge source, a concept in the SUMO, and the name of the other knowledge source
     supertype:  pm#relation_from_string (pm#string,*)
        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