Originally Posted by
nkedel
Y and F were are as close to universal as you're going to get, and virtually all non-low-cost airlines use these for the basic, interline-able, full-fare coach and first respective.
There is actually a standard for these things (google on "IATA Resolution 728 Code Designators for passenger ticket and baggage check") but airlines alter how they use them pretty much at will. (Trivial example -- with no supersonic service any longer, R is now Premium Economy on some airlines and 1st-class-suites on others.)
LCCs that don't sell through the GDS systems may or may not use this kind of fare code at all.
Quite right, about Y and F. I am sorry, meaning of F was not in question all. The point was made about classification of B and M.
Regardless of IATA, airlines do use designations at will as you acknowledged yourself. In some classes R is not a purchased bucket at all. It could be an award or an upgrade bucket too.
I am not sure what your issue was when I said that his interpretation of Y, B and M is not universal. You seem to be saying what I did, that different airlines use the same letters for different classes, except YFCJ.