Nothing is absolutely flat.   Less flat and more flat are out there, of course. Plus flat enough and not flat enough.  All of those, plus flatter, flatter than that and then flatter still.  Almost flat, too, and not quite flat.  Ultra flat and simply not flat.  And let’s not forget the flattest and the least flat.  We can qualify flat endlessly and compare flatnesses infinitely.  But still nothing is absolutely flat.

Just how is it that there can be so many variations of that which does not exist?

(Photo taken by me on the Hasselblad 500CM with Ilford FP4+ @ 200 and developed in ID11)