The schedule tracking system is called Programme Delivery Control.

For instance, Programme Delivery Control signals-used by video recorders for starting/stopping recording at the correct time even during changes in programming-are sent as teletext packets.

Programme Delivery Control - The coded teletext delivery programme called PDC/StarText.

This means it will not compensate for a disrupted schedule due to live sporting events or news bulletins, but many video recorders with these systems also incorporate Programme Delivery Control (PDC) and will use that to alter times if possible.