RUSA defines randonneuring like this:
Randonneuring is long-distance unsupported endurance cycling. This style of riding is non-competitive in nature, and self-sufficiency is paramount. When riders participate in randonneuring events, they are part of a long tradition that goes back to the beginning of the sport of cycling in France and Italy. Friendly camaraderie, not competition, is the hallmark of randonneuring.
Like any kind of cycling, people have different goals, but a common one for randonneurs is to ride Paris-Brest-Paris (PBP) which happens every 4 years including 2011. To qualify to ride PBP, you have to ride a 200K, 300K, 400K, and 600K brevet. The day I rode there were 200K, 300K, and 600K riders. In fact I think there were more doing the 600K than any other distance.
So I did the longest ride I have ever done, but it was the shorest route being offered. But I did find the common attitude of being self sufficient and pushing through are certainly shared between randoneering and bicycle commuting.
In particular this ride was done in rainy and cold weather and finished after dark. So my experience with choosing clothes for daily commuting conditions gave my confidence that I was picking the right thing to wear. Finishing after dark was not a problem because I knew my lights would work. After all, I have been using them everyday, twice a day, while commuting during the short winter days.
My only real problem was with the new waterproof gloves I bought just before the ride. I will talk about them more tomorrow.