anchor.diff:  (define-resource sponsorship ()
     :class (s-prefix "bravoer:Sponsorship")
     :properties `((:amount :double ,(s-prefix "schema:amount"))
  -		(:created :date ,(s-prefix "dcterms:created"))
  -		(:modified :date ,(s-prefix "dcterms:modified")))
  +		(:created :datetime ,(s-prefix "dcterms:created"))
  +		(:modified :datetime ,(s-prefix "dcterms:modified")))
     :resource-base (s-url "http://data.bravoer.be/id/sponsorships/")
     :has-one `((event :via ,(s-prefix "bravoer:sponsored")
   		     :as "event")
  
positive.code:                 (:clef :string ,(s-prefix "music:clef"))
                  (:file :string ,(s-prefix "nfo:fileUrl"))
  		(:name :string ,(s-prefix "nie:title"))
  		(:created :date ,(s-prefix "dcterms:created"))
  		(:modified :date ,(s-prefix "dcterms:modified")))
    :resource-base (s-url "http://data.bravoer.be/id/parts/")
    :has-one `((score :via ,(s-prefix "nie:isLogicalPartOf")
                              :as "score"))
  
negative.code: 		(:instrument :string ,(s-prefix "music:instrument"))
  		(:email :url ,(s-prefix "vcard:hasEmail"))
  		(:birthdate :date ,(s-prefix "vcard:bday"))
  		(:created :datetime ,(s-prefix "dcterms:created"))
  		(:modified :datetime ,(s-prefix "dcterms:modified")))
    :resource-base (s-url "http://data.bravoer.be/id/contacts/")
    :has-one `((address :via ,(s-prefix "locn:address")
  		      :as "address")
  