Sleep-Request Revocations
If any routine in the sleep queue denies a sleep request, the Power Manager sends a sleep-request revocation to every routine that it has already
called with a sleep request. Your routine must reverse whatever steps it
followed when it prepared to receive a sleep demand. A communications
application that prevents users from opening new sessions while it is waiting
to receive a sleep demand, for example, might once again allow users
to open new sessions.