Well… my 5D Mk III has the green square for Auto mode, and Canon has a sense of humour. The manual says about that mode: “If you did not obtain the desired color tones, change the shooting mode to <P/Tv/Av/M>, set a Picture Style other than <[ * A]>, then shoot again.”
My 1Ds on the other hand has only P, Tv, Av, M and bulb.
Why P mode? Works great with a Cannon flash set to ETTL, even if you are bouncing flash. So why not?