application, so it can be used to provide long-term
locking (for example, conference room scheduling).</p>
      <p>In order to use the locking subsystem in such a general way, the
applications must adhere to a convention for identifying objects and
lockers.  Consider a conference room scheduling problem, in which there
are three conference rooms scheduled in half-hour intervals. The
scheduling application must then select a way to identify each
conference room/time slot combination.  In this case, we could