Some aditional info I have for AF:

L: Economy Long Haul (earns only 25% of the miles).
M: Economy for CIO (Caribean Indian Ocean) Flights
S: Alizé (Premium Eco for CIO Flights)
Y: Full fare Economy
Z: Discounted Business

Based on the order they appear in the systems I would assume that the price order is as follows:

First class: P F A

Business: J C D I Z O
(Note that "I" seems to be business and not economy)

Economy: Y B K H W T V L N X

But stand to be corrected !