files on a hddvd

[earl]

i see on a hddvd a lot diferent files
.evo .. that is the movie with audio?
for waht are .map file? i see a lot of .map files, for earch .evo file is a .map file - what does .map files do?
what is the directory "ADV_OBJ" ?
what is the directory "HVDVD_TS"?
(menus).aca are the menu in a hddvd?
what does .xpl files do?
for backup a movie, only the main movie from my hddvd i do need only the .evo file? nothing more?

[earl]

questionmark

[KoD]

Probably nobody answers because everybody believes you should check the Decrypting section of the forum first.