I have a HAM-CDG-HAM on AF, E on the way out and N back. I see in the terms and conditions that both legs can be amended both before and after departure for 50 euros. I take it that this is the result of the new fare structure introduced a couple of months ago and much discussed elsewhere here.

Does anyone know if there is a time limit on the changes? I will use the first leg, but if I "miss" the return does that mean that if I pay 50 euros, I basically have an open ticket to use at some future date, or is there a catch? And when it says amendable, does that mean I could even change destination, say a CDG-BCN, which sounds way more appealing than a CDG-HAM?

Many thanks for your insight/experience/willingness to read the fine print.