It's any two flights you can list on using your travel card, that depart at least 1 hour apart that get you to your domicile at least 1/2 hour prior to check-in. You also have to register a normal point of departure (where you are commuting from), so I don't think you can call from Paris and exercise the commuter clause.
I list on mainline flights, though depending on where you are coming in from, you could list on Comair, ASA, ACA, or whoever is running the flight for Delta Corp.
If you don't make it in, they can go back and pull up the Deltamatic (love that name, so George Jetson) computer records and confirm that you did or didn't list and attempt to board (i.e. check in and end up on the airport standby list) which would preclude trying to jumpseat in on a non-Delta affiliated flight.
Good luck in class.