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The PLAY statements (event trapping) enable, disable, and suspend play
event trapping.
 
PLAY ON
PLAY OFF
PLAY STOP
 
Usage Notes
    ■ PLAY ON enables play-event trapping. A play event occurs when the
      number of notes in the background-music queue drops below the limit
      you set in the ON PLAY statement. If a play event occurs after a
      PLAY ON statement, the routine specified in the ON PLAY
      statement is executed.
    ■ PLAY OFF disables play-event trapping so no trapping takes place
      until another PLAY ON statement is executed. Events occurring while
      trapping is off are ignored.
    ■ PLAY STOP suspends play-event trapping so no trapping takes place
      until a PLAY ON statement is executed. Events occurring while
      trapping is suspended are remembered and processed when the next
      PLAY ON statement is executed. However, remembered events are
      lost if PLAY OFF is executed.
    ■ When a play-event trap occurs (that is, the GOSUB is performed),
      an automatic PLAY STOP is executed so that recursive traps cannot
      take place. The RETURN from the trapping routine automatically
      executes a PLAY ON statement unless an explicit PLAY OFF was
      performed inside the routine.
    ■ If your program contains event-handling statements and you are
      compiling from the BC command line, use the BC /W or /V option.
      (The /W option checks for events at every label or line number; the
      /V option checks at every statement.) If you do not use these
      options and your program contains event traps, BASIC generates the
      error message, "ON event without /V or /W on command line."
    ■ For more information, see Chapter 9, "Event Handling" in the
      Programmer's Guide.