I have a PDF ticket from the Austrian Federal Railways (ÖBB) for an ÖBB Nightjet train from Germany to Switzerland (not going through Austria). The PDF includes the following text:
In Österreich akzeptieren wir Ihr PDF-Ticket digital (Anzeige auf Laptop,Tablet, Smartphone). Grenzüberschreitend drucken Sie dieses bitte auf weißem Papier A4 Hochformat aus.
In Austria we accept your PDF ticket digitally (display on laptop, tablet, smartphone). Crossing borders, please print it on white A4 paper in portrait format.
(my translation)
I understand that some operators can only handle paper tickets, but in this case the whole route is operated by ÖBB. Do I really need to print the ticket, just because I'm not actually in Austria?