On the FS2020 we just installed on the RV-8, when looking down on the valve from the top handle, the center (forward) fittings are of course for the main fuel feed output going to the filter/electric boost pump or a fuel injector's return line coming from a pump. The fittings on the left side go to the left tank, and the ones on the right side of the valve body go to the right tank.
I confirmed this by visual inspection looking inside the holes in the fittings, and also blowing air thru them while turning the handle from left to right before the valve was ever installed.