I've been looking over the doc for modding and it leaves much to be wondered over. Perhaps using the lua itself and the logging out some of this might be teased out, but I would assume the following questions should be answered by the doc, but if it is currently I'm not seeing it.

For instance if I wanted to make it possible to use a hammer on grass to convert the tile from dirt with grass on it to turf... I don't see how to do that. I don't see how to add to or modify what actions a particular held item (or maybe more specifically a tool). I also do not see how to convert a tile into one which has turf on it.

Perhaps this information is in there already. I see a function to change a tile type, but I don't see a type listed that seems to pertain to dirt with turf on it. Perhaps the "Raised" type? I'm just not sure. Is having turf even part of the tile type data or is having turf placed on type something else? Given how many layers some tiles can have I think a small section that describes how tiles are structured could be useful. For instance dirt tile with turf on it with some type of flooring on that and then a building over that seems like several layers of different things that can live together. If turf is just the "raised" type then one of those gets removed, but still thats the base tile type and then the flooring and then a building.