Identifiers in the Web

• URL: locations
  • New York Public Library, second floor, third aisle, second shelf, third book from left
• URN: location-independent names
  • QP:475.L95; ISBN:0-19-854529-0
• URC: descriptions
  • genre: book, title: The Ecology of Vision;
    author: J.N.Lythgoe; Date: 1979;
    Publisher: Clarendon Press, Oxford