Unlike Windows where associating one data file with a particular program automatically associates all programs with the same three character suffix (or file type) with that same program, associating a given data file with a particular program via the properties notebook in OS/2 associates only that file with the program. Other data files of the same type are unaffected.
With OS/2 version 4 fix pack one, IBM decided to add a rexx command file that would partly plug this gap and allow you to associate all multimedia files with a given suffix with the same program. This command is called setdefv.cmd and it can be found in the os2 directory of your OS/2 boot drive.
The easiest way to find out more about this program is to go to the command prompt and type in setdefv without any parameters. This will bring up a help screen containing useful examples of how to use the program.
The reason that the command only works with multimedia files is because the information about the file associations set by this program are stored in the \MMOS2\MMCLSSET.INI file which is only referenced by multimedia applications.
This article written by Stephen Chapman, Felgall Pty Ltd.