Originally Posted by
thijsseh
The above is completely correct, but just for clarity: O class is also a Business Class Saver fare, which you can just book with cash.
Still kind of confusing, I see that O Class is a classic rewards (use miles to book). if I see offer available on a one-way ticket and ability to upgrade to next class with Miles, is that also O class?
How and when do you find saver level class availability and why would this only be of use for upgrading a saver level ticket usually a few days before departure?