I would imagine a fair number of tickets checked are to stations that are not served by the service you're on, but may be served by another service at a station you call at. For example: You are the guard on a service from Tring to Euston calling at various stations including Milton Keynes, Watford Junction, and Harrow and Wealdstone, before going directly to Euston. You check the ticket of a passenger, and they are going to Wembley Central. Presently, you have to say that this ticket is invalid, even though the passenger was probably going to change trains at Harrow and Wealdstone (given that this is the only way to get from Tring to Wembley Central). Now, I am not suggesting that we should have complete route knowledge of all possible paths and changes, because that would be absurd, but if there was an itinerary next to the ticket that shows a change of trains at a station that you call at, it would remove the need for the route knowledge that a guard has. It would also help with San Bernadino Line services that have to be split halfway, since a ticket from San Bernadino to LA Union would currently be invalid on the first half of the journey. After the changing station has passed, and if the passenger has not disembarked, then you would have the icon to check their ticket appear again, and, seeing that they have missed the changing point on their itinerary, you could then say that their ticket is invalid. This could also work the other way, where the starting station is not on your service, but the itinerary states that they changed onto your service from another at a station that is on your route, allowing the ticket to be valid. This is probably a nightmare to program, but I thought it was a nice idea to improve Conductor Mode.
