Relation rdfs#label (?,string)  in WebKB, with FO, use the link '_'
  supertype:  name (pm)
  equal:  label
  subtype:  name (entity,Literal)  a relation between an instance of a concept and the name (instance of a concrete data type) of that concept; the name has to be a lexically meaningful name
  subtype:  has-pretty-name (?,string)
  subtype:  has-variant-name__hasvariantname (?,string)