For a person being watched to temporarily permit keyboard control by
   a watcher who could not otherwise have it:

   1. To successfully use the PERMIT_INPUT hot-key to temporarily permit
      a watcher to have keyboard control, the user being watched must
      currently have control of his keyboard.

   2. Enter the PERMIT_INPUT hot-key.

      As shipped, the default hot-key value for PERMIT_INPUT is
      <CTRL-P>A. (The obvious choice, <CTRL-P>P, is already in
      use for /PREVIOUS, so <CTRL-P>A was chosen instead. The
      "A" stands for ALLOW which is a synonym for PERMIT.)

   3. If the hot-key is accepted, this means the PERMIT_INPUT was
      successful and a watcher will now be able to do a REQUEST_INPUT.

      The hot-key will just beep if the PERMIT_INPUT isn't accepted.

      (PERMIT_INPUT will not be accepted if the hot-key is not defined,
      or if you are currently being watched with Peek/Spy and the
      watcher currently has control of your keyboard.)

   4. After a successful PERMIT_INPUT has been done by the user being
      watched, a watcher who wants temporary keyboard control can use
      his REQUEST_INPUT hot-key to request it.

   5. If the REQUEST_INPUT by the watcher is accepted, he will be able
      to use his TOGGLE_INPUT key to toggle input with the user he is
      watching.

      Or if the permitted watcher has PSIMUL, then both the permitted-
      watcher and the user being watched will be able to type at the
      same time. (See the top-level PEEK Subtopic: Watching
      /PSIMUL_INPUT.)

   6. If the REQUEST_INPUT hot-key entered by the watcher just beeps,
      this means his REQUEST_INPUT wasn't successful.

      This could mean that another watcher has already requested, and
      been granted, temporary keyboard control. (Only one watcher at
      a time may have REQUEST_INPUT.)

      Or it could mean that the PERMIT_INPUT has been revoked.

   7. PERMIT_INPUT is revoked when the user being watched toggles
      his PERMIT_INPUT back off again by entering his PERMIT_INPUT
      hot-key a second time.

      If there is a primary watcher, PERMIT_INPUT granted by the user
      being watched is also revoked whenever the primary watcher takes
      over keyboard control.

   8. A permitted watcher who currently has REQUEST_INPUT can
      relinquish it at any time by entering his REQUEST_INPUT
      hot-key a second time.

      This would allow another watcher to then do a REQUEST_INPUT in
      order to gain temporary keyboard control.