Did you know that the letter F on your boarding pass means first class and that Y means economy?
What about Z or X or L or Q? What do they mean?
When you book online, those letters do mean something. For instance, it means whether a ticket is refundable or not. It also means whether your ticket can be upgraded.
These letters are about fare distinctions. If you’re really not sure about the ticket you’re about to purchase, you can always call the airline or go to their website to see what that letter means.