Nikon Digital Cameras Reference Manual page 22

Rotating Photograph Thumbnails
Selected photograph thumbnails in the browsing window can
be rotated ninety degrees to the left by selecting Rotate Se-
lected from the Edit menu or clicking the
button in the toolbar. (Movie file thumbnail can not be ro-
tated.)
Select the thumbnail with the right mouse button and choose Rotate
from the right-button menu.
Rotating the selected thumbnail.
Rotate Selected
Rotations applied to thumbnails in the browsing window have no effect on
the image files in the camera, or on copies of the image file that have
already been saved to disk. Rotations are saved if the image file is copied
to disk after having been rotated.
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