Relation pm#rhetorical_relation (description_content/medium/container,description_content/medium/container)  main sources: the Rhetorical Structure Theory (RST) and the PENMAN ontology; DO NOT USE such fuzzy relations: instead, use relations from/to situations!
  subtype:  presentational_rhetorical_relation  subject_matter_rhetorical_relation  symmetric_rhetorical_relation  opposition  negative_consequence
  supertype:  relation_from_description_content/medium/container (description_content/medium/container,*)
     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