ON PLAY                  Trap for Background Music Remaining

 ON PLAY(queuelimit) GOSUB {linenum | linelabel}

    Establishes a subroutine to which Turbo Basic will branch if fewer
    than a specified number of notes remain in the background music
    buffer. The trap must also be turned on by means of a PLAY ON
    statement.

  queuelimit    An integer expression specifying the number of notes to be
                trapped.

     linenum    The first line of a music-handling subroutine. Setting
                linenum to 0 disables trapping.

   linelabel    A label identifying the first line of a music-handling
                routine.

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      Notes:    With trapping in effect, and when Turbo Basic is executing
                music in the background mode, when the number of notes
                remaining is fewer than queuelimit, Turbo Basic branches
                to the specified subroutine and temporarily suspends
                trapping (by means of an implicit PLAY STOP statement).
                Trapping automatically resumes when a RETURN from the
                handling subroutine is executed (unless the handler
                explicitly performs a PLAY OFF or PLAY STOP).

                With event trapping in effect, Turbo Basic checks for the
                specified event after each program statement. The $EVENT
                metastatement can be used to turn event trapping on and
                off at specified points within a program.

                The size of the music buffer can be set by means of
                $SOUND.