I think what you have here might work, but another option might be a dictionary with (only) keywords `xmin`, `xmax`, `ymin`, `ymax`.

An (easy to implement) alternative would be to allow `slice` objects or, more generally,  anything that you can do ``somearray[section]`` on.  That would be trivial to implement, but would allow for situations like weird overscans that aren't rectangular or something (not sure if that exists in the wild, but you never know...).