This function sends a message to the I/O procedure associated with a file that was opened with mmioOpen.

#define INCL_MMIOOS2
#include <os2.h>

HMMIO     hmmio;    /*  Open file handle. */
USHORT    usMsg;    /*  Message #. */
LONG      lParam1;  /*  Message information. */
LONG      lParam2;  /*  Message information. */
LONG      rc;       /*  Return codes. */

rc = mmioSendMessage(hmmio, usMsg, lParam1,
       lParam2);