Over the years, I've had a great many schedule changes that usually result is a ticket reissue. Not when times are adjusted by a little, but I can't recall when I have not had a reissue when the flight numbers (and times) change - especially on an international trip. I currently have a trip where all flights started on AA and still are on AA, and airports are all the same. But a schedule change forced a change in flights. AA tells me all things are in order they did not have to reissue under these circumstances - and I suspect they are right. Just wondering if anyone can definitively say when tickets must be exchanged versus just revalidated (or whatever the correct terminology is.) Thanks in advance.