As far as I know (and I admit, I dont' know much) DPN is based on race results. What is SCHS and Texel based on?

Is one of them based on math, i.e. a measure of the boats, length, weight, sail area, etc. put that into a formula and come up with a number that is used instead of race results? I don't want to see this turn into the old 12 meter AC rule, but I think design input can produce a fair number.