I find it weird to use TODO for something you don't actually have to do. But you're apparently not the only one to do this, and as long as everyone who's working on the same code is on the same page it's fine I suppose.

I think in these same three categories but label them TODO, T0DO, and TOD0, respectively. I like that they look roughly the same when visually scanning through a file but are easy to grep for separately.