Originally Posted by
golfmad
Isn't it the case that some fare conditions change after an upgrade (e.g. removal of some flexibility on an otherwise flexible ticket)? If that's the case then if you undo an upgrade does the ticket become more flexible again?
AIUI, the underlying fare retains its original conditions (as condition 9 above makes clear). The flexibility of the upgrade is different, but it doesn't change the flexibility of the underlying fare.