An ARK provides extra services above and beyond that of an ordinary URL. Instead of connecting to one thing, an ARK should connect to three things:

In a web browser, for example, if you enter

it returns a brief machine- and eye-readable metadata record, such as


    who:   (:unav) unavailable

    what:  Truckee River, below Truckee Station, looking towards Eastern

            Summit. -- Photographer's number: 222 -- Photographer's series:

            Central Pacific Railroad, California.

    when:  (:unav) unavailable


It is a side-benefit of ARKs that an object's metadata doesn't need an identifier different from that for the object, which cuts in half the number of identifiers that need to be generated and managed.