Super Smash Bros. Ultimate Ripping Project

[Essential]

I only just now realized something; What are all the textures called "mtl", "rgh", "spc", and "ao"? They are present in the models hosted on the website but if I check the .7z files listed on this thread, they're nowhere to be found.

What are they and how are they obtained?

Sorry to throw you in the material page but...
https://github.com/ScanMountGoat/Smush-M...extures.md

Also some of textures called "mtl", "rgh", "spc", and "ao" could be obtained in the channels of the prm maps and normal maps