Relation pm#relation_to_situation (*,situation)  in WebKB, prefer using relations "from" a situation
  exclusion:  spatial_relation_to_entity_with_spatial_feature  relation_to_time  relation_to_collection  relation_to_attribute_or_quality_or_measure
  subtype: {relation_from_time_to_situation relation_from_situation_to_situation}
  similar_to:  participation  involvement_by_reference
  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