Originally Posted by
KayVeeBee
Public transport fares work om a “time and space” basis. So you will get a ticket valid for a certain time (a couple of hours) and a certain space (a number of zones). Within that time and space you are free to travel. The connection you select in the app will be used to determine the starting time, and the zones for the ticket, but you are not limited to those trains. In your place I would purchase the ticket once i landed from a ticket machine though. I don’t count on my phone working in a foreign country.
I think I have the answer. When you click through to the purchase screen, the following terms show (In German).SingleTicket is valid for a trip from the start municipality / city to the destination town / city on the commercial road, within the VRS network and entitles to change trains / roundabouts, and return trips are provided at night. The validity period is 360 minutes. It is not transferable.
However, when you start with a route search you can select a date and time, but that only seems to be a way to see your options, when you click through the "Buy" it looks like you are buying a ticket with immediate validity for the time period after the moment of purchase.