721 recording question

I just got a 721 and I see that when you program a show to record, it shows the time and channel instead of the show name. Does this mean it is just recording that timeslot without regard for what show is on? For example, I set it to record ER. If ER is not on for some reason, will it still record whatever NBC shows in that time period, or does it know to only record ER?

Thanks,
Dennis