The was ready to ship in principle any cargo in return for payment. And therefore, the basic key – price controlled key – was that Jews were going to be shipped to Treblinka, were going to be shipped to Auschwitz, Sobibor ... so long as the railroads were paid by the track kilometer, so many pfennigs per mile. The rate was the same throughout the war, with children under ten going at half-fare and children under four going free. Payment had to be made for only one way. The guards of course had to have return fare paid for them because they were going back to their place of origin ...