ON STRIG(n)              Trap for Specified Joystick Button

 ON STRIG(n) GOSUB {linenum | linelabel}

    Establishes a subroutine to which QuickBASIC will branch if a
    specified joystick button is pressed. The trap must also be turned on
    by means of a STRIG(n) ON statement.

           n    A numeric expression indicating the button to be trapped.
                Must be 0, 2, 4, or 6. The meaning of n is as follows:

                0   button A1
                2   button B1
                4   button A2
                6   button B2

     linenum    The first line of the joystick-handling subroutine.
                Setting linenum to 0 disables trapping.

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

   -----------------------------------------------------------------------

      Notes:    {linenum | linelabel} must be defined at the main program
                level.

                With trapping in effect, QuickBASIC checks to see if the
                specified joystick button has been pressed. When the
                button has been pressed, QuickBASIC branches to the
                specified subroutine and temporarily suspends trapping (by
                means of an implicit STRIG(n) STOP statement). Trapping
                automatically resumes when a RETURN from the handling
                subroutine is executed (unless the handler explicitly
                performs a STRIG(n) OFF or STRIG(n) STOP).

                Downstrokes that cause joystick button trapping do not set
                functions STRIG(0), STRIG(2), STRIG(4), or STRIG(6).

                All event trapping is temporarily disabled when QuickBASIC
                is executing an error-handling routine (established via an
                ON ERROR statement).

                If the "Checking Between Statements" option is in effect,
                QB checks after each statement. If the "Event Trapping"
                option is selected, QB checks after each new program line.
                If neither option is selected, no trapping takes place.

                For command-line compilation, /v enables checking after
                each statement, and /w enables checking after each new
                line. If neither switch is used, no trapping takes place.