.AMG Files - What are they?

So I'm searching through some dreamcast files and I find a .amg file. What is this file, and how does the dreamcast use it? I looked this up on extension finders and whatnot, but to no avail. They say it could be an archive of some sort, but I found nothing online that deals with these files. Anybody know anything?

Greetings. This is my first time actually helping someone else out here. This link should have all the info you need about .AMG files.

http://www.liutilities.com/products/...ary/files/AMG/

Thanks for the reply! I may not have been very clear in my first post. I had already been to that site you linked to, as well as many others that were similar. I know what an .amg is, but not how it's used on the dreamcast. Has anyone ever worked with one before? Any information would be greatly appreciated.

EDIT: I just thought I'd let you know why I'm so interested. I recently started making custom Guitar Hero II Songs, and I love it. I thought maybe I could disect Samba De Amigo and start making custom songs for that. It would be awesome. I know how to replace the audio, and these AMG files look like they are the data. Anyone heard like this?

MORE EDIT: Over the past two years, I've been dissecting these .AMG files. It seems they are specifically for the Samba de Amigo family of games, possibly standing for AMiGo. I've been figuring out what the contents of the files mean, and my progress is trackable at http://customsamba.blogspot.com