Flexibility in timing on pre-booked nsb.no train tickets?

If travelling around Norway via train using pre-booked tickets from nsb.no, are the tickets explicitly ONLY valid for the stated train departure, or would they be valid on an equivalent route?

eg. If I miss an r10 train from Oslo airport to Oslo S, could I catch any r10 train? Any similar train (eg. the r11)? Or would I pay a penalty?