Upvote:4
No, when you book a ticket from point A to B then you have the right to travel only from A to B. That is because you pay only for the journey from A to B and not O to T.
If there are other passengers who book tickets from O to A or B to A, the same seat might be allotted to them for those legs of the journey. In case there are no bookings for those legs, the seat will be vacant.