I thought I had a good handle on the way airlines allocated award inventory however I faced a new hurdle today. While trying to book one award ticket on delta and one on CO i noticed that CO did not have any award seats on AS but delta showed 4 available. Both carriers were looking at W class, but CO showed 0 and DL 4. Similar issue with CO from MAN-EWR. NW and CO both showed seats available but DL did not. Any thoughts?