Until someone more knowledgeable comes around, you may want to have a look at the Wiki - here - where a number of fare codes are explained.
You might also still be able to go to the Refunds site, enter your ticket number and before actually requesting a refund be able to read the detailed fare rules if you did not do so as you booked.
Last edited by JDiver; Apr 5, 2017 at 3:10 pm
Reason: Remove. Onfunctional URL