Nikon D810 - Manual (Page 364)

340
At the default setting of MTR > under > over (H), exposure,
flash, and white balance bracketing are performed in the order
described on pages 135 and 140. If Under > MTR > over (I) is
selected, shooting will proceed in order from the lowest to the
highest value. This setting has no effect on ADL bracketing.
e8: Bracketing Order
G
button ➜ A Custom Settings menu