D700 (high??)ISO banding
This type of artifact I have not seen on D700. What I did see at ISO 6400 and above is a grid-like pattern across the very dark areas of the image. It is not common enough, however, to bother me much, but I do look for it now, after I came across it a couple of times.
|Black on White by RaVN11|
|Hummingbird and Bee by dibilio57|
from A Big Year - birds
|xheneta iseni _for DPReview by Mike Slade|
from - My Fair Lady - (Portraits in Full Colours Only + A Border)