What is the concept between the cutouts seen on some raceboards?

When people put a concave cutout in a speedboard is that more useful for the front foot or rear foot? Does it help with edging? What about toe side? Is this design of board more useful for course racing or speed?

I'm contemplating making a convex cutout only on the left foot toside of my fixed session. My thinking is it will be easier to go from heelside to toside downwind with my left foot foward only. Or would it be better if the cutout was by my hindfoot to strengthen toeside edging?

Jake

I think they do it because that part of the board is not in use and only takes away speed and does not help to go upwind further.

The speed guys already did this in the beginning. Now you see more and more twintip race boards cutting away parts of teh tip. So did the Danish guys, Armin Harich (4th. PKRA Germany, best twintip) and Alberto Rondina (4th PKRA tour ranking, best twintip).

but still, looks like directionals are the way to go...so try one to see if it is a difference in going upwind...