Originally Posted by
Wunk
(...)
Business - Classic Award & Upgrade (O) - This one seems pretty clear to me. Seat available for upgrade with miles. (which I've never been able to get any availability of on any trans-continental flight over the past 12 months
)
O is the fare bucket INTO which you will go if you either buy a classic business class ticket with miles or upgrade from Eco/premoium eco TO business class with miles.
Business - Flex Award for Elites (C) - I have no idea what this is. I'm guessing that Plat members (I'm gold myself) can apply for this award? But is it an award ticket or a miles upgrade?
C is a paid full flex business class fare; paid with either money of miles (I did not know C was for Flex Award, but if you say so, I assume it to be right)
Business - Upgrade with DL SWU/Global Upgrades & Fare Class (Z) - This is the one where you can upgrade with vouchers from AF/KLM or their partners I think?
AFAIK, there are no upgrade vouchers with AF/KLM.
Z is discounted business class fare (leasure). Never heard of this fare bucket applying to awards.