Default [Q] What are file format of firmware flash files ".img" (inside the .tar.md5)

Hello,

Sorry, evtl. could someone help me: What are the file formats of the mlo, cache, factoryfs, hidden and modem files in those evrywhere available "nameblabla.tar.md5" files? SquashFs?

Evtl. could someone provide me links to Android dev pages for that, before I get mad in googlin for.

Thanks
(BTW: Admin, couldn't post it in SGS 2 9100 R&D cause too less "posts")