Well, my primary goal of it was to get the two selections Shelves and Lakes as separate selections. If you select all terrain between altitude -1000 and 0, you have no way of telling if it's a continental shelf, or a section of landlocked water that goes below sea level. It's a personal thing, but two of the things I first want to change with each of my maps is that the continental shelves are too wide if you compare them to Earth's, and that finding and filling all those basins around the map by hand is tedious. Hopefully with these, I can do that. Getting there is a bit of a brute force, but that's all that was available to me.