StartDocPort

BOOL StartDocPort(
    HANDLE  hPort,
    LPTSTR  pPrinterName,
    DWORD   JobId,
    DWORD   Level,
    LPBYTE  pDocInfo
);

Performs the tasks it takes to start a print job on the specified port.

Returns TRUE if the operation is successful.

hPort	The handle of the port to which the print job is being sent.
pPrinterName	Points to the zero-terminated string that is the name of the printer to which the job is being sent.
JobId	Identifies the job being sent to the spooler.
Level	The job level.
pDocInfo	Points to the document information.

The StartDocPort function is called at the start of a print job. The StartDocPort function in your port monitor should setup whatever is needed for your port monitor to print the data that will be provided in subsequent WritePort function calls.