hdc (HDC) - input
hrgnDst (HRGN) - input
hrgnSrc1 (HRGN) - input
hrgnSrc2 (HRGN) - input
cmdMode (LONG) - input
CRGN_OR
pInstance (PVOID) - input
lFunction (ULONG) - input
rc (LONG) - returns
RGN_ERROR
Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. Error codes for conditions that the handling routine is expected to check include: