Originally Posted by hugochan
Class of service just talk about the broad picture, and restrictions. Like on United, F means full fare, refundable First Class ticket, while V means highly discounted Economy, which is usually non-refundable, and non-upgradable for international travel, except 1K members w/ SWUs. But the fare rules are actually rules that the agents supposed to follow, when booking your trip, or helping you when you need to change anything on the tickets.
Actually, class of service doesn't really tell you anything about fare restrictions. Although it is usually the case the F (1st class) fares are refundable, there have been some that are not. And though usually the low fares such as V or W are non-refundable, there are V, W, H and other low fares that are refundable. This often occurs when a major carrier such as UA is matching a fare of a low cost carrier.
I don't mean to be nit-picky or contradictory, but it really is only the fare basis that determines any of the rules and restrictions, not the class of service.