The order of subclasses mean differently for originating cities. K in USA, may be a higher subclass bracket than K originating in say, Europe.

M class may seem a higher fare bracket than K. And V class? One would think it's at the bottom of the hierarchy? Not if it's originating from some asian cities for their one year ticket. M class seems to be used for short validity tickets.

It really is difficcult to gauge which fare bracket is what. One needs to know where the ticket is originating from first.