Dear Ben,
One of my questions is still pending: If you travel from say Châtelet to Versailles and you have a Carte Orange for 2 zones, in what station do you buy your supplementary billet Ile de France to get to Versailles? At the end of your 2 zones, or at the beginning of your journey at Châtelet? Do prices differ if you buy the billet closer to Versailles?
