This function is called from MCDs to return message to applications. Returned information includes command status, cuepoints, position changes, playlist messages, and device specific events.

#define INCL_MMIO
#include <os2.h>

USHORT    usDeviceID;  /*  Device ID for message. */
HWND      hwnd;        /*  Window handle. */
USHORT    usMsgType;   /*  Notification type. */
USHORT    usUserParm;  /*  User-defined. */
ULONG     ulMsgParm;   /*  Message-defined. */
ULONG     rc;          /*  Return codes. */

rc = mdmDriverNotify(usDeviceID, hwnd, usMsgType,
       usUserParm, ulMsgParm);