The PrtFilterJobEnd function is called to inform the print data filter DLL that a print job is about to end. This allows the DLL to provide custom processing and send special data to the print server at the end of a print job.
void * WINAPI PrtFilterJobEnd(
void *UniqueID,
char **pBufPtr,
DWORD *pBufLen
);
No data is passed in the buffer, but the user DLL can return print data which will be sent to the printer before the print job is ended.