Single ticket for the RER (fast train) from Orly ORY airport to central Paris or vice versa. Your RER ticket includes the Orlyval monorail which runs from Orly-Sud terminal via Orly-Ouest to the Anthony RER station where you can catch the RER train to central Paris.
Your RER ticket will work up to any Metro/RER station within zone 1 or on any stop on the RER B line between Antony and Gare du Nord.
Please note: If you decide to physically leave the underground system during your journey, your ticket will no longer be valid.