Dr. Adrian Corcoran:

This is everything you go through in the airport, whether it is security, the capacity of the terminals, the stands for the aircraft or the runway. Most of those have what we call hard constraints. We set the capacity and then the co-ordinator, independent of the airport and airlines, allocates those into slots. In most cases, the parameters are hard constraints. Once they hit the constraint, they stop. The referral parameters that the Deputy mentioned on CBP and terminal 2 check-in desks are handled somewhat-----