The MMPMMMIO.INI file is in the directory specified in the MMBASE environment variable.
The DLL name (szDLLName field) specified in the MMINIFILEINFO structure must follow the same naming conventions as the DosLoadModule function. If the DLL or procedure name is invalid, an error is returned.
Any changes this function makes to the MMPMMMIO.INI file do not affect the MMIO internal data structures until the next time the DLL is loaded. This means that in the case of an addition, for example, the I/O procedure added is not active until the next time the MMIO.DLL is loaded.
In a deletion, the entry is removed and the entire file is rewritten to prevent it from growing with deleted entries. This is due to the way the OS/2 functions handle deleting entries from INI files in general. They do not reuse deleted entries.
If an error occurs during the loading of MMIO.DLL because the I/O procedure or procedure name cannot be validated, MMIO.DLL will still be loaded, but that particular I/O procedure will not be linked. The user must program for such situations.
Note: When MMIO services builds its internal structures for the I/O procedures, it processes the MMPMMMIO.INI file as a stack. The result is, the last I/O procedure in the file is the first one called during processing. Thus, in the MMPMMMIO.INI file, enter last those I/O procedures that you want to process first.