What does "Sharp to the edge" actually mean?

[F15Rules]

17 minutes ago, michael.h.f.wilkinson said:

A simple way to test whether the EPs where at fault is to rotate them in the binoviewer, which is easier than rotating the whole binoviewer. I have never noticed any difference in sharpness between top and bottom and left and right edges (until I started using varifocal glasses, obviously). EPs are generally very close to perfectly rotationally symmetric, so I would not expect any difference between the north-south and east-west edges

I refer you to my last post of last Thursday 3 or 4 posts back..🙂

Dave