I know there's a heated debate on this subject. I had to switch mine over for slalom a few years back. Funny, huh? There's SS class in other disciplines.
I'll see if I can find anything out, if you get an answer, let me know (via pm), as I'm deciding if I want to sneak in and compete.
Here's the link I have for the "RuleBook"*:
http://www.usacycling.org/forms/NORBA_rulebook.pdf
*note: the start of the pdf files is blank, just scroll down to the contents page, etc.