NetworkOverrides
RUL (INI Type) 0x10000002
This file has one large section, titled [RuleOverrides]. It works by saying that if two textures are aligned next to each other like this:
Tex1|Tex2
Then the resulting textures will be applied Tex1a|Tex2a
This is the format:
ID1,Rot1,Flip1,ID2,Rot2,Flip2=ID1a,Rot1a,Flip1a,ID2a,Rot2a,Flip2a
ID1=InstanceID of the left tile ID2=InstanceID of the right tile ID1a=InstanceID which replaces the left tile ID2a=InstanceID which replaces the right tile
These particular rules are VERY powerful, since one line makes them work in all four cardinal orientations. The left/right perspective is not set in stone to a cardinal direction. Rather, the right side of Tile1 has to border the left side of Tile2.
Also, having zeros in the ID1a and ID2a spots causes a bad draw (red line). This is to keep things from being constructed which don't look right, but still conform to all the other RULes.