son of 3 leg 1 eye dog ..
Kind of OT I guess, but what does a 90% vs. 100% handicap league mean?
Cats ... It means the better player spots the lessor player 90% of the difference between their ratings in lieu of a 100%. I think you will agree that beginning players tend to get better faster than better players improving their ratings. 90% handicap says that the lessor player has to play 10% or better than average to beat the better player.
This way, the better player is not being punished for being better, and the lessor player has to improve their game to win. It, basically, keeps everyone improving their game, and not just being the best for a particular handicap like a 100% handicap does.