/ONCE
   /NOONCE  (default)

   Limits ALLOWed watching to a single time. When watching by the
   ALLOWed user is terminated, he will not be able to watch your
   terminal again until you again do a PEEK/ALLOW command for him.

   /ONCE is a DCL positional qualifier. It can be used at the start of
   a PEEK/ALLOW command line, before any identifiers, in which case it
   applies to all identifiers on the command line. It can also be used
   on a PEEK/ALLOW command line after a particular identifier, in
   which case it will apply only to that one identifier in the list.

   Examples:

         $ PEEK/ALLOW/ONCE J_JONES,J_DOE
         $! J_JONES and J_DOE may watch you only once each.

         $ PEEK/ALLOW J_JONES,J_DOE/ONCE
         $! J_JONES and J_DOE may watch you but J_DOE only once.

   ALLOW/ONCE has no effect on SPY, nor on privileged PEEK users.