I think he’s talking about the different graphical tiles that walls use based on surrounding walls - the ├, ┌, ┼, etc. More specifically, I think he wants to make one T-wall image and automatically rotate it when making a tileset, instead of making four different ones.
I think this is a problem better addressed with the graphics tool than the game proper, though. Some tilesets don’t want the wall graphics to be simple rotations of each other.
Edit: Or maybe it’s the other way around, and the code is automatically rotating one image but he wants it not to? I’ve never tried making tiles, myself.