hmmio (HMMIO) - returns

A handle is returned to use with further calls to MMIO functions to perform I/O. This handle is not a file system handle. Do not use this with such operations as OS/2 file system read, or write.

NULL is returned if the file cannot be opened. See the exception for the preceding ulOpenFlags parameter flag MMIO_DELETE. If the pmmioinfo parameter is not NULL, the ulErrorRet field of its MMIOINFO structure will contain extended error information returned by the I/O procedure. If delete fails, ulErrorRet contains MMIOERR_DELETE_FAILED. The error return can also be queried by calling the mmioGetLastError function. See Return Codes for a description of MMIO Manager error codes.