What exaction do you mean?
Who can help me, give me a REZ Perspective
REZ files are like RAR files, they store the the protected contents of crossfire like
-Shooting sounds
-Textures
-Texture maps
-Etc...
If they are combined (extracted to the same place) you get a full directory view (i mean there is no shattered files in them)
They are protected to the CrossFire title licence so modifiying them is illegal...