Originally Posted by
IAN-UK
Well, yes it was. Then Lufthansa worked out it could make more cash by introducing variation in some levels of service in exchange for modest supplements to any booking class. So now, it seems that what you get is governed by a mix of booking class and any supplementary package you opt for. It's not usually possible to engineer a move upwards in booking class (and miles-earnings) by selecting one of the "flex" options presented.
Well... not
quite.
Yes, the principle of branded fares system as it is used well nigh universally today at least in Europe is such that the underlying fare bucket (letter) is the same across all branded fares you might be selecting from at the same time.
It is also true that before this became the way to do things, you'd have specific fare buckets tied to a given brand, i.e. K,L,T would be "saver", Y,B,M would be "flex" or "full fare" and the rest would be simply "Economy" or perhaps "semi-flex".
However the details like stopovers, routing allowed, minimum stay, max stay, advance purchase and so on were still more granular than the letter. Just as the letter L today actually represents a fare code for example
L06CLSE8 it could, and still can, represent a code L06CLSEV - both of these are L and both of these are Classic. In this case one of them is one-way, and another a return, but there is no reason why the difference could not be the advance purchase requirement.