Once upon a time, way back in the depths of history, the railway and ferry companies of Europe got together and decided it would be a wonderful thing if their tariff systems could be harmonised in a way that might allow the international traveller to buy a train ticket from Stockholm to Paris or from London to Berlin. Thus was born the TCV (tarif commun international pour le transport des voyageurs), a simple but decidedly useful facility that allowed us to cross the continent using any number of trains and ferries with just a single ticket for the entire journey.
In many parts of the continent, the TCV fares still serve as the basis for international tickets. But more and more train operators.