Why is the future T12 called a tram-train?

As you will have noticed, the T12 has a specificity that sets it apart from the majority of trams.

Indeed, the tram-train is a vehicle derived from the tramway, capable of running both on tram tracks in urban areas and on the rail network.

Between Massy and Épinay-sur-Orge, the tram-train will follow the current route of the RER C and will then replace the RER. From Épinay-sur-Orge to Évry, it will switch to tram mode