> You have a good grasp of booking classes and fare rules.
Thank you - clearly too much time spent reading FT!

One final question - if I am in possession of an A ticket, and want to make a change, but the flight I want to change to looks like:
T9 E9 W9 I9 R9 D9 C9 J9 A0 F1
What are my options?

I'm quite sure I could upgrade to F, but I suspect in most situations this would be unaffordable.

I suspect this might depend on the subtleties of the fare rules, but is it generally possible to voluntarily downgrade and sit in J or W without having to start again with a whole new ticket?