The MMPMMMIO.INI file is in the directory specified in the MMBASE environment variable.

The DLL name (szDLLName) specified in the CODECINIFILEINFO structure must follow the same naming conventions as the DosLoadModule function. If the DLL or procedure name is invalid, an error is returned.

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 how OS/2 functions delete entries from INI files. Deleted entries are not reused.