Fuzileer;
You've already heard what the capping is... As to the airlines, they are the ones who asked to do it here. When asked what they could do to get off and not take a delay due to congestion, they were advised that in some areas they could take them FL230 and below... They much prefer this to staying on the ground or getting miles in trail through an effected sector. We did some of that today at work. It caused some flights to go about 300 miles or so at the lower altitudes before they could get up to more efficient altitudes...
regards
Scott