for cross-border journeys with final destination abroad, you need to print the ticket on white A4-format paper in portrait print setting. Within Austria, we will accept your PDF Ticket also in digital format
@kitten I had one grumpy night train conductor who are very angry that I didn't print that out in Croatia. But at the end he allowed me to enter anyway
@kitten that reads to me as a "We can't guarantee that everyone across the border will accept it in digital form, therefore you should print it"... But I could be wrong