Originally posted by 2 Many Miles:
Award tickets do have greater flexibility than normal tickets. You can make "minor" changes to them, such as date of travel any time. I think you can also change the routing as long as the city-pairs stay the same.
As for co-terminals, there is no "official global co-terminal" list. Rather, each specific fare specifies what co-terminals it allows as part of the fare rules.
AA had allowed me to change FF ticket between the two airports recently after the tickets were issued without a charge. The explanation given at the time was the EWR and JFK were co-terminals and I was not changing the city pair. Interestingly enough, when I wanted to change the arriving city from MBJ to KIN on another ticket last year they wanted to charge me $50 to do so.