So I've been reading about these instruments a bit just seeing how they work. I see talk of 1/10 arc-second resolution for checking surface plates. Looking at specs of one of these I've seen for sale, a K&E 71-2022, it says resolving power is 3.4 arc-seconds. So is resolving power the same as resolution? That seems like it wouldn't be accurate enough if so. If they are not the same thing, what's the difference?