For a primary watcher to temporarily permit keyboard control by a
   secondary watcher:

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

   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 secondary watcher will now be able to do
      a REQUEST_INPUT.

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

      (PERMIT_INPUT will not be accepted if the hot-key is not defined,
      or if the primary watcher doesn't currently have keyboard control.)

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

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

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

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

      This could mean that another secondary watcher has already
      requested, and been granted, temporary keyboard control.
      (Only one secondary 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      Or it could mean that the PERMIT_INPUT has been revoked.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 primary watcher toggles his
      PERMIT_INPUT back off again by entering his PERMIT_INPUT
      hot-key a second time.

      A PERMIT_INPUT done by the primary watcher is also revoked
      whenever the user being watched takes back control of the
      keyboard from the primary watcher.

   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 secondary watcher to then do a
      REQUEST_INPUT in order to gain temporary keyboard control.