MAC1, MAC2, and MAC3 are tile changing commands with pretty sparse documentation.
Stumbled upon this while trying to create a trench digging chapter.
MAC1 - Swap out both the graphics and the tile properties.
MAC2 - Do the tile change, but only swap out the graphics. Tile properties are the same as the original tile.
MAC3 - Swap out both the graphics and the tile properties AND play the water sound effect heard in Night of Farewells.
Wait, using MAC2 you could feasibly create a map that has any tile acting like any other tile if you create a terrain map first then use MAC2 to load the aesthetic tiles over it.
for the record (and anybody else who wants custom sets), I will be perfectly willing to explain all parts of what I did to anyone who asks. The only thing that’s happening in the meantime is making it less tedious gruntwork (and i may not make fee3 deadline)