I'm looking to leave my car for a few days at Cornavin while I go to Paris and I see that if you are using the train for long distance travel you can get a discounted rate, for which you need to get your parking ticket validated at the train ticket office.

Does anyone know if this also applies if your train ticket is bought through SNCF rather than SBB???  The SNCF ticket is much cheaper for the same route.