ProMods

I feel these are related to this thread.

What is in the DESC files? They are often not even written (not present at all for many sectors) to after changes. I've noticed that AUX files tend to be the ones that get written to most often, and seem to hold object coordinates. Does anybody know what data sets each of the 4 files hold?

Editor loads maps from the folder alphabetically but does it do with A being highest priority and Z lowest or is it the opposite?

.desc tells the game "Hey, you have to load this sector, there's something inside" (that's why it doesn't change, it's created when the sector starts to exist)
.data - contains brush information
.aux - I think it contains some data about map UI. If you hide roads/prefabs from the map, this file will be modified
.base - all other stuff. Models, terrain, bezier patches etc.

"A" will be loaded first, "Z" will be loaded last.