Relation higgins#attribute (Higgins_ContextObject_or_DigitalSubject,Higgins_Attribute_or_Value)  Instances of this property are used to point to one or more values (i.e. cases where (i.e. cases where the range is higgins:Value). One instance (at most) may also be used to point to a holder of metadata (an instance of higgins:Attribute) about the entire set of values.
  supertype:  Higgins_object_property (pm)
  subtype:  uniqueIdentifier (DigitalSubject -> String)
  subtype:  relation (Higgins_ContextObject_or_DigitalSubject,SubjectRelationship)  A directed relation between two Digital Subjects
     subtype:  correlation (Higgins_ContextObject_or_DigitalSubject,SubjectRelationship)  A directed relation between two Digital Subjects believed to represent the same underlying Entity
  subtype:  firstname (Person,NormalizedStringSimpleAttribute)
  subtype:  surname (Person,NormalizedStringSimpleAttribute)
  subtype:  postalAddress (Person,PostalAddress)
  subtype:  streetAddress (PostalAddress,String)
  subtype:  city (PostalAddress,String)
  subtype:  state (Higgins_ContextObject_or_DigitalSubject,String)
  subtype:  postalCode (PostalAddress,String)
  subtype:  country (PostalAddress,String)
  subtype:  friend (DigitalSubject,SubjectRelationship)