Now can someone please explain what do those double wall directions in fact mean:
dfhack/library/TileTypes.cpp:
{ "smooth stone wall RD2", WALL, STONE, VAR_1, TILE_SMOOTH, "--SS--E-" },
{ "smooth stone wall R2D", WALL, STONE, VAR_1, TILE_SMOOTH, "--S---EE" },
{ "smooth stone wall R2U", WALL, STONE, VAR_1, TILE_SMOOTH, "N-----EE" },
{ "smooth stone wall RU2", WALL, STONE, VAR_1, TILE_SMOOTH, "NN----E-" },
{ "smooth stone wall L2U", WALL, STONE, VAR_1, TILE_SMOOTH, "N---WW--" },
{ "smooth stone wall LU2", WALL, STONE, VAR_1, TILE_SMOOTH, "NN--W---" },
{ "smooth stone wall L2D", WALL, STONE, VAR_1, TILE_SMOOTH, "--S-WW--" },
{ "smooth stone wall LD2", WALL, STONE, VAR_1, TILE_SMOOTH, "--SSW---" },
{ "smooth stone wall LRUD", WALL, STONE, VAR_1, TILE_SMOOTH, "N-S-W-E-" },
{ "smooth stone wall RUD", WALL, STONE, VAR_1, TILE_SMOOTH, "N-S---E-" },
{ "smooth stone wall LRD", WALL, STONE, VAR_1, TILE_SMOOTH, "--S-W-E-" },
{ "smooth stone wall LRU", WALL, STONE, VAR_1, TILE_SMOOTH, "N---W-E-" },
{ "smooth stone wall LUD", WALL, STONE, VAR_1, TILE_SMOOTH, "N-S-W---" },
{ "smooth stone wall RD", WALL, STONE, VAR_1, TILE_SMOOTH, "--S---E-" },
{ "smooth stone wall RU", WALL, STONE, VAR_1, TILE_SMOOTH, "N-----E-" },
{ "smooth stone wall LU", WALL, STONE, VAR_1, TILE_SMOOTH, "N---W---" },
{ "smooth stone wall LD", WALL, STONE, VAR_1, TILE_SMOOTH, "--S-W---" },
{ "smooth stone wall UD", WALL, STONE, VAR_1, TILE_SMOOTH, "N-S-----" },
{ "smooth stone wall LR", WALL, STONE, VAR_1, TILE_SMOOTH, "----W-E-" },
?