Cache File (Content Management)

A cache file (.map) is a collection of tags compressed in a only file to be load by the game engine. The engine use cache files to load levels but there are 4 types of cache files.

Level Cache File (name_of_the_level.map)
All the level content as the level itself is stored in a name_of_the_level.map.

Bitmaps Cache File (bitmaps.map)
All the Halo PC and Xbox bitmaps are stored in the bitmaps.map file.

Sound Cache File (sound.map)
All the Halo PC and Xbox sounds are stored in the sounds.map file.

User Interface Cache File (ui.map)
The user interface is stored in the ui.map file.

About Halo Custom Edition
On the retail version, bitmaps and sounds cache files are keep separates because levels share sounds and bitmaps. If sounds and bitmaps were stored inside each invividual level, their sizes would be huge especially as the size of all Halo's files would be uselessy heavy...

But with CE version, customized maps can be created with customised content so the previous solution can't be applied to the CE version and sounds and bitmaps cache files doesn't exist.