mmioDetermineSSIOProc processes the MMIOINFO data first to check for a storage system I/O procedure specified in the fccChildIOProc field. If it is not NULL, the fccChildIOProc is returned as the storage system FOURCC. Otherwise, the file name is parsed for a separator character; if one is found, the extension is converted to the storage system FOURCC. In this case, mmioDetermineSSIOProc returns the parsed string that consists of those characters following the separator character. The name is parsed from left to right.