Hoping this hasn't been asked too annoyingly often...
Say there are two routes from A to B: one via X and one via Y. (There is also a direct route X-Y.) A return ticket from A to B is valid on either route, A-X-B or A-Y-B. (As it happens, it is also valid A-X-Y-B, if this is relevant.) There exists also a station Q, which is between X and A. Like this:
Obviously, the straightforward circular journey A-Y-B-X-A is allowed. But what about moving the start/end point around the circle, to start at Q? With a return from A to B (or B to A), is it allowed to go Q-A-Y-B-X-Q? (Every station is either a change of train or a point where the through service calls.) Or would this also need something like a single Q-A to legitimise it?
Say there are two routes from A to B: one via X and one via Y. (There is also a direct route X-Y.) A return ticket from A to B is valid on either route, A-X-B or A-Y-B. (As it happens, it is also valid A-X-Y-B, if this is relevant.) There exists also a station Q, which is between X and A. Like this:
Obviously, the straightforward circular journey A-Y-B-X-A is allowed. But what about moving the start/end point around the circle, to start at Q? With a return from A to B (or B to A), is it allowed to go Q-A-Y-B-X-Q? (Every station is either a change of train or a point where the through service calls.) Or would this also need something like a single Q-A to legitimise it?