Relation pm#Higgins_annotation_property (?,?)
  subtype:  higgins#base  higgins#fractionDigits  higgins#length  higgins#maxExclusive  higgins#maxInclusive  higgins#maxLength  higgins#minExclusive  higgins#minInclusive  higgins#minLength  higgins#pattern  higgins#totalDigits
  supertype:  pm#Higgins_property (?,?)
     supertype:  pm#relation_coming_from_an_ontology (*)
        supertype:  pm#relation_for_an_application (*)  relation introduced by an application
           supertype:  pm#relation_playing_a_special_role (*)  this type permits to categorize relations according to their roles ; this is a traditional but quite subjective 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