Mine was just a sensor thing (they might have swiped it at the tills but it had a sensor system for the doors to gain access to school). That's why they were annoying though because if you forgot your card you couldn't get into school lol and also the fact that you never need money means that you'll probably forget to bring some to top it up at the machine. I don't think it was until I was in like year 10 or 11 when we got them though so I always had money with me and by sixth form we went out for lunch anyway.
OH YEAH AND I'm sure they used to monitor what people were eating and not allow them to get too much junk food or something. Although the vending machines and pretty much all the junk food was long gone by then (nice one Jamie Oliver ;l). I never did this but some kids used to use their free dinners repeatedly at the different food counters (we had three different bars) so they could get more free stuff but the cards stopped that one because it was all on the screen :P

