Unlikely they are flat on the base...but anything's possible.
I like 1° base, 3° sides, and sharp all the way around the tips & tails. (If the sharp tips & tails sounds scary, how about getting them sharp and carrying a pocket stone on the hill. If they hook...which mine don't...dull them as needed.)
If you're usually on dry snow and want quicker initial response when edging, try 0.75° base angle, maybe feathered to 1° at the tips & tails. If you're a slalom racer on dry snow, try 0.5°.
If you're in lots of rocks and want a smaller chunk of edge knocked out when you hit a rock, start with 2° sides and increase to 3° when you get better coverage.
Base edge angle is best set by the shop when the bottoms are stone ground. After that, very few of us should do anything with the base edges except use a stone or diamond to remove any burrs pushed up by rocks. Limit your sharpening to the sides.