This function opens a file for unbuffered I/O or buffered I/O (including RIFF I/O). The file may be a DOS file, a memory file, or an element of a custom storage system (provided that a custom I/O procedure has been installed using mmioInstallIOProc).

#define INCL_MMIOOS2
#include <os2.h>

PSZ          pszFileName;  /*  File name. */
PMMIOINFO    pmmioinfo;    /*  Pointer to MMIOINFO. */
ULONG        ulOpenFlags;  /*  Flags. */
HMMIO        hmmio;        /*  MMIO file handle. */

hmmio = mmioOpen(pszFileName, pmmioinfo, ulOpenFlags);