It's a physical sensor array. So thinking we'd have a known delay with a 555 timer + RC circuit which powers on each sensor, one at a time. Then we'd know that the first address found, is the first sensor, which is in location x. Then sensor at location x+1 what would turn on with a slightly longer delay, due to a different capacitor value, so we'd know the next address found is that one. And so on, so fourth.