Relation higgins#simpleValue (SimpleValue,DigitalSubject)
  subtype:  string  normalizedString  base64Binary  integer  dateTime  boolean  decimal  nonNegativeInteger  positiveInteger  nonPositiveInteger  negativeInteger  float  double  long  int  short  byte  unsignedInt  unsignedLong  unsignedShort  unsignedByte  hexBinary  time  date  gYear  gYearMonth  gMonthDay  gDay  gMonth  anyURI  token  nMTOKEN  language  name  nCName
  supertype:  simpleMetadata (Value,DigitalSubject)  Used as the super-Property of some DatatypeProperties whose domain is higgins#ValeAndMetadata or higgins#DigitalSubject to indicate that these properties are considered to be metadata about the ValueAndMetadata (or DigitalSubject)
     supertype:  Higgins_datatype_property (?,?)
        supertype:  Higgins_property (?,?)
           supertype:  relation_coming_from_an_ontology (*)
              supertype:  relation_for_an_application (*)  relation introduced by an application
                 supertype:  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:  relation__related_thing__relatedthing___related_with  type for any relation (unary, binary, ..., *-ary) and instance of pm#relation_type