This function provides the number of I/O procedures that match the specified data format.

#define INCL_MMIOOS2
#include <os2.h>

PMMFORMATINFO    pmmformatinfo;  /*  Indicates field type. */
PLONG            plNumFormats;   /*  Number of supported formats. */
ULONG            ulReserved;     /*  Reserved. */
ULONG            ulFlags;        /*  Reserved. */
ULONG            rc;             /*  Return codes. */

rc = mmioQueryFormatCount(pmmformatinfo, plNumFormats,
       ulReserved, ulFlags);