PLAY ON, PLAY OFF, and PLAY STOP Statements Details
 
Syntax
  PLAY ON
  PLAY OFF
  PLAY STOP
 
These statements are used with the ON PLAY statement to trap play
events. When a PLAY OFF statement is executed, the event-trapping
subroutine is not performed and the event is not remembered.
 
A PLAY STOP statement does not perform the event-trapping subroutine,
but the subroutine is performed as soon as a PLAY ON statement
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 subroutine automatically
performs a PLAY ON statement unless an explicit PLAY OFF was
performed inside the subroutine.