Ref. this thread: http://www.catsailor.com/forums/sho...54&an=0&page=0#Post54954

http://www.f20.nl/ -> click on "Reglement". That is as good as I know.
As far as I know, there has been no news on this topic since 2005.. The "F20" rules you see on that webpage is tailored to the N20 in one of its versions (not trying to provoke anybody, I just know that there has been a few versions around the world). The Hobie Fox 20 was also supposed to measure in to the "F20" rules as you see them on that page.
There is a lack of fitting designs, rules and most importantly, dedicated people to get a F20 class going.

Why did you ask, SCHRS?