Eventually it will contain all ceiling tiles for the tic tileset.
And yeah. those tiles with corridor elements in it drive me crazy. I have some concepts for doing the ceilings on them. The difficult part at these ceilings is that it all needs to be architectural correct AND ingame useful - i test the tiles with several character including big creatures like balors and dragons; if the creature clips through the ceiling something went wrong.
I think you mean this tile:
I intend to use the same wood seam in this tile as everywhere but we'll see.
I am in contact with Gimlor and we divide the work currently. I think the most difficult part is the corridor tiles. Ever looked at them closely with ceilings in mind? bah... i have no idea how put a proper looking ceiling on it (yet).
Here is an example of such a corridor element:
I will also close as many polygon gaps as possible where you can look through objects from a low camery angle (e.g. the shelves in the library).
edit: I just happened to pick one of the difficult tilesets for making ceilings. The amount of different tile groups alone makes it much more difficult and the shape of the tiles doesnt make it easier.
I should have chosen the normal town interior with the tavern and merchant tile groups

... we'll they will be next ... eventually