the rules differ based on where the tix are issued. i.e. an Asian issued ticket allows only one stopover for free in Asia. the rule differences are mainly related to such stopover restrictions.

to answer your question though - with a ticket issued in Asia you are permitted 6 segment and 3 stopovers in North America. However the limit is such that if you do the 3 stopovers before 6 segments you lose the balance of the segments - same way if you do 6 segments before 3 stops you lose the remaining stops

i dont know of any place you can get the rules online. except for australia originating fares try www.travel.com.au