Relation higgins#attribute (pm#Higgins_ContextObject_or_DigitalSubject,pm#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:  pm#Higgins_object_property (pm)
  subtype:  higgins#uniqueIdentifier (higgins#DigitalSubject -> higgins#String)
  subtype:  higgins#relation (pm#Higgins_ContextObject_or_DigitalSubject,higgins#SubjectRelationship)  A directed relation between two Digital Subjects
     subtype:  higgins#correlation (pm#Higgins_ContextObject_or_DigitalSubject,higgins#SubjectRelationship)  A directed relation between two Digital Subjects believed to represent the same underlying Entity
  subtype:  pwa#firstname (pwa#Person,higgins#NormalizedStringSimpleAttribute)
  subtype:  pwa#surname (pwa#Person,higgins#NormalizedStringSimpleAttribute)
  subtype:  pwa#postalAddress (pwa#Person,pwa#PostalAddress)
  subtype:  pwa#streetAddress (pwa#PostalAddress,higgins#String)
  subtype:  pwa#city (pwa#PostalAddress,higgins#String)
  subtype:  pwa#state (pm#Higgins_ContextObject_or_DigitalSubject,higgins#String)
  subtype:  pwa#postalCode (pwa#PostalAddress,higgins#String)
  subtype:  pwa#country (pwa#PostalAddress,higgins#String)
  subtype:  pwf#friend (higgins#DigitalSubject,higgins#SubjectRelationship)