MONITOR

typedef struct _MONITOR{
	BOOL (WINAPI *pfnEnumPorts)(LPWSTR pName, DWORD Level, LPBYTE pPorts,
			DWORD cbBuf, LPDWORD pcbNeeded, LPDWORD pcReturned);
	BOOL (WINAPI *pfnOpenPort)(LPWSTR pName, PHANDLE pHandle);
	BOOL (WINAPI *pfnOpenPortEx)(LPWSTR pPortName,LPWSTR pPrinterName,
			PHANDLE pHandle, struct _MONITOR FAR *pMonitor);
	BOOL (WINAPI *pfnStartDocPort)(HANDLE hPort,LPWSTR pPrinterName,DWORD JobId,
			DWORD Level,LPBYTE pDocInfo);
	BOOL (WINAPI *pfnWritePort)(HANDLE hPort,LPBYTE pBuffer,DWORD cbBuf,
			LPDWORD pcbWritten);
	BOOL (WINAPI *pfnReadPort)(HANDLE hPort,LPBYTE pBuffer,DWORD cbBuffer,
			LPDWORD pcbRead);
	BOOL (WINAPI *pfnEndDocPort)(HANDLE hPort);
	BOOL (WINAPI *pfnClosePort)(HANDLE hPort);
	BOOL (WINAPI *pfnAddPort)(LPWSTR pName, HWND hWnd, LPWSTR pMonitorName);
	BOOL (WINAPI *pfnAddPortEx)(LPWSTR pName, DWORD Level, LPBYTE lpBuffer,
			LPWSTR lpMonitorName);
	BOOL (WINAPI *pfnConfigurePort)(LPWSTR pName, HWND hWnd, LPWSTR pPortName);
	BOOL (WINAPI *pfnDeletePort)(LPWSTR pName, HWND hWnd, LPWSTR pPortName);
	BOOL (WINAPI *pfnGetPrinterDataFromPort)(HANDLE hPort, DWORD ControlID,
			LPWSTR pValueName, LPWSTR lpInBuffer, DWORD cbInBuffer,
			LPWSTR lpOutBuffer, DWORD cbOutBuffer, LPDWORD lpcbReturned);
	BOOL (WINAPI *pfnSetPortTimeOuts)(HANDLE hPort,LPCOMMTIMEOUTS lpCTO,
			DWORD reserved // must be set to 0);
} MONITOR, FAR *LPMONITOR;

MONITOR contains pointers to the functions that implement a print monitor. It is a member of the MONITOREX structure.

A monitor should set pointers for unimplemented routines to null.