It would be great if they explicitly said it. The only possible reference I see is:
"Les usages Modem sont autorisés et décomptés de votre crédit."
http://assistance.orange.fr/le-forfa...fre-7447.php#5
But I don't even know if "usages Modem" means the same thing as tethering or more specifically, the "Personal Hotspot" feature in the iOS UI.