UV nesting would be a different way to handle the UV coordinates that are exported by MoI.

Right now it uses just a simple system where every separate surface in a solid gets texture coordinates that span from 0,0 to 1,1 - that's across the entire texture image.

So for example say you have a cube and you put a texture on it using the UV coordinates generated by MoI - each face of the cube would have an identical full image displayed on it. If you were to paint on a face to modify the texture map, you would see the same paint applied to all the other faces as well.

UV nesting would change this so that each different face of the cube would be situated in its own smaller piece of UV space. With each face having its own separate chunk of mapping space it means that each one is independent so for example if you were to paint on one face to modify the texture map, it would only affect that one face and the other faces would remain unchanged.

- Michael