SIC LOCK

        [SIC\]SIC LOCK [LockFile]

    With  no  argument,  display the list of lock files owned by the current
    program session. With a file name as argument, create  this  file  as  a
    lock  file.  Attempting  to create a lock file which already exists is a
    fatal error. Lock files owned by the current  program  session  are  im-
    plicitely deleted when exiting.

    This command is intended to protect some user's resources, e.g. invoking
    it in a procedure ensures that this procedure can not be  run  twice  in
    the same or in another session.