I agree with AusTXHiker on the fare issue.
Here is a copy of the Class of Service codes from about 2 years ago. There might be a few new ones added since then.
A - First Class Discounted
B - Coach Class Discounted
Bn- Night Coach Discounted
C - Business Class
Cn- Night Business Coach
D - Business Class Discounted
E - Shuttle Service
F - First Class
Fn- Night Coach in First Class Compartment
H - Coach Class
J - Business Class Premium
K - Coach Class Discounted
Kn- Night Coach Discounted
L - Coach Discounted
M - Coach Discounted
N - Coach Discounted
P - First Class Premium
Q - Coach Discounted
Qn- Night Coach Discounted
R - Supersonic
S - Coach
T - Coach Discounted
U - Shuttle Service
V - Coach Discounted
Vn- Night Coach
W - Coach Premium
Y - Coach
Yn- Night Coach
Z - Business Class Discounted