It's a box within FLY which shows the DUT list, which is associated with flights. If you do a search on DUT in this forum you'll get plenty of speculation and relatively little specifics, but it's not purely status or CIV driven, there's a much wider set of aspects brought into play, including fare and whether the passenger could be enticed to pay for the higher cabin in future travel. It's totally computerised though and if I was in charge of BA I would ensure the algorithm was totally secret, and with a random number generator in there just to fool us.