ERTMS is the European Railway Traffic Management System composed by the onboard equipment and all the line side and trackside equipment necessary for supervising, in real-time, the train operation according to the traffic conditions.
ETCS (European Train Control System) is its vital part.

It is the system, conceived in various levels of application, for being superimposed to the different European national signalling systems, in order to provide interoperability and controlling, in a seamless way, the European network as a whole.

Madrid-Barcelone H.S. line
Vienna-Budapest line
Italian H. S. network