suppose you want to travel from outside the london travelcard area on a paper ticket to a zone 6 national rail station and then continue on the same train using oyster. of course if you have oyster pay as you go then you need to get off the train, touch in and wait for the next train. what happens if you have a travelcard product on your oyster? if you stay on the train (so don't get off to touch in) and then leave then train in zone 2 where there are no barriers, get on a tube without going through barriers and touch out leaving at a barried tube station what happens? what happens in the reverse direction? thanks