> Apparently those files are just ISOs, and you just need to rename them. I also
> heard that Firestarter is good at handling various types of CD image formats.
>
> There may be some linux commandline utilities to convert between the various
> formats, some of them are just shell scripts and don't require any compilation.
>
> I don't know why they don't just use BIN/CUE or ISO for everything.

MDS is an A120 proprietary version of CUE. I haven't played around with it too much, since I try to avoid it (CUE/BIN, too; don't like two-file disk images), but it seems to be a binary type file instead of the plaintext that CUE uses. MDF can be an ISO, if there's no other info saved in it. Start playing around with stuff like "data precision measurement" or subchannel data and all bets are off.