Ride levels

I know I've seen it somewhere but a Google doesn't get me there. I'm trying to find a list of the ride levels. I think there are five (standard, xxx, extreme, gold, and insanity) and for mile eater statis there are certain requirements so knowing the order would help.
I've got 5 ToH Extreme Rides and wonder what level they are considered. Is "extreme" one of the levels?
Multi day rides - I have 3 3000 in threes and one 5000 in five. What level are they?