Yaiyuewai53
Every country has own rules. In Austria, this rule applies:
Yes, PDF tickets can also be viewed on laptops, tablets and smartphones within Austria. A photo ID with proof of age and, if applicable, a discount card must be presented with the ticket. The PDF ticket must still be printed on paper (A4 portrait format) for journeys to and from other countries.
However, you start your journey in Austria and it is the same staff until Zurich. They can certainly read your ticket as PDF file on your smartphone.
@RolandP Could you confirm this?