Got my Cotswold Audax brevet card back in the post a few days ago. Audaxes are conducted under the regulations of the Audax Club Parisien. As you go around the route, you get your card stamped at each checkpoint. At the finish (or arrivée in Audax-speak), your card is send off to be validated. I don't know quite what the entails, but I'd like to think that somewhere in France a Gallic cycle-elf had to write out a little index card with my name on the top of it.
Not sure when I'll next do an Audax, but am toying with the idea of doing a 50km ride on the 8 Freight with Hal-baby in the back. Slightly worried other riders might think I'm taking the micky.