rc (LONG) - returns
The return value is 0 if the function is successful; otherwise, it is an error value.
If the error returned = PMERR_DRVR_NOT_SUPPORTED, the graphics engine will unload the hooking DLL and work as though no routine were installed. This would be the case if the hooking DLL only handled 32-bit entry points and received a display dispatch table of 16-bit entry points.