From what I can tell it looks like from the bottom up: R1, R1, R2, R3, R4, R4 all OEM profile. It matches the "closest" row of the normal keyboard area. R1 is like the arrow keys and Z through /, R2 is like A through ', R3 is like Q through ] and R4 is like Esc through = and the F1 -> F12 keys.
With DSA profile sets it doesn't matter, the keys are all the same profile.