A display grabber also includes several extended functions. Windows calls the extended functions by supplying an extended-function number in the AX register when it calls the standard function InquireGrab. The InquireGrab function uses the extended-function dispatch table, consisting of function offsets, to transfer control to the desired function. This table differs from the standard-function dispatch table because it contains offsets, not jump instructions.
The extended-function dispatch table has the following form:
ExtFuncTable label word
dw Obsolete ;function 0FFF4h
dw Obsolete ;function 0FFF5h
dw Obsolete ;function 0FFF6h
dw Obsolete ;function 0FFF7h
dw GetBlock ;function 0FFF8h
dw Obsolete ;function 0FFF9h
dw GetVersion ;function 0FFFAh
dw DisableSave ;function 0FFFBh
dw EnableSave ;function 0FFFCh
dw SetSwapDrive ;function 0FFFDh
dw GetInfo ;function 0FFFEh
dw Obsolete ;function 0FFFFh