Welcome to Flyertalk.

In the example you gave, those are classes of service for that airline. It gets complicated because in many cases, the class of service on one airline may not mean the same on another airline.

There is usually a guide in each airline's forum explaining their classes.

For general terms, under help there's a menu selection for glossary that may help.

As an example, from this thread http://www.flyertalk.com/forum/unite...-glossary.html

the booking codes for United are:

Ticketing Classes
A: Discounted Fare First Class. Round The World First is booked in this class.
B: Almost Full Fare Economy with minimal restrictions - also used Star RTW
C: Full Fare Unrestricted Business Class
D: Discounted Fare Business - used also on all "Business" Class Star RTW fares
E: 'Ted' and some low web/discount fares from early 2005. (Was 1K coach award to early 2004. Also known as 'NY' class)
F: Full Fare Unrestricted First Class
G: Travel Industry Economy Class fares
H: Higher level Economy Class with few restrictions. Some "RTW" coach is H
I: Business Class UPGRADE AWARD from Economy (Better known as 'NC' class)
K: Seasonal Economy Promotional Fares/Reduced Fare Gov't contract etc
L: Discount Fare Economy with a lot of restrictions
M: Almost Full Fare Economy with few restrictions
N: Economy Class AWARD TICKET -- free ticket using miles (Better known as 'XY' class)
O: Business Class AWARD TICKET -- free ticket using miles (Better known as 'XC' class)
P: Premium USA Transcon First Class on 3 classers
Q: Discount Economy with moderate restrictions. (Bereavement tix are in Q)
R: First Class AWARD TICKET -- free ticket using miles (Better known as 'XF' class)
S: Real Lowball Economy with lot of restrictions. Not always mile earning
T: Heavy discount Fare Economy - often with a lot of restrictions
U: Showed up Nov/03 as booking class for "TED" also in mid 2005 a high level mainline class!
V: Discount Fare Economy often with a lot of restrictions
W: Discount Fare Economy often with many restrictions
X: First Class UPGRADE AWARD from paid Business (Better known as 'NF')
Y: Full Fare unrestricted Economy class
Z: Deeply discounted Business Class, available on some international and domestic (ps) flights. Note that Z class fares are generally NOT upgradeable to F/P with any instrument (miles, 500-milers, SWUs or CR-1s)

Other Codes
Q-up: Discounted "A" fare
Y-up: Another discounted F booking code