            SWITCHON key.ch INTO
            $(
              CASE 'B':
              CASE 'C':
              CASE 'D':
              CASE 'E':
                   // Set a break flag (ctrl/B to ctrl/D break) in the
                   // current task.
                   setflags(current.task, 1 << (key.ch - 'B') )

              CASE 'N':
                   reading.break.key    := FALSE
                   outflags     := outflags | flag.input.request.to.send
                   IF key.ch='B' UNLESS read.pkt.queue=0
                   $(   outflags := outflags & ~ flag.message.to.print
                        RESULTIS CUR.ABANDON
                   $)
                   BREAK // No action - ignore break
            $)


