The 2 letter date code is pretty easy to keep track of.
It's based on the ten letter word "AUTHORIZED".
A=1
U=2
T=3
H=4
O=5
R=6
I=7
Z=8
E=9
D=0
That means the first would be an EO.
So there would be EO, ER, EI, EZ, EE, DD, DA, DU, DT, DH, DO, DR, DI, DZ, DE, AD, AA, AU, AND AT.