Straight off the UA Website.
http://www.united.com/page/article/0,,1181,00.html
Code:
Class of service Booking class Award miles1 Elite status miles/segments1
Business C D J Z 125% 100%
Economy Y B E H M O Q U V A 100% 100%
No Mileage Credit X I L G S K P N T W 0% 0%
Y = Full Economy Flexi
B = Economy Flexi
M = Economy Flexi
H = Economy Flexi
Q = Economy Flexi-Saver
V = Economy Flexi-Saver
W = Economy Flexi-Saver
T = Economy Flexi-Saver
L = Economy Smart Saver
S = Economy Smart Saver
G = Economy Smart Saver
K = Economy Smart Saver
P = Economy Smart Saver (Domestic Grab-A-Seat/Trans Tasman short term Economy Sale) - Generally not valid for Longhaul.
F = Economy Smart Saver (Domestic Grab-A-Seat special ie $1 specials) - short term
X = Economy Redemption/Award (ie Star carrier economy redemption class)
N = staff category - subload/non-subload