Updated AIC (Ammunition Identification Codes) list:

T1IBW = 265 rds Cal .50 linked, AP M2
T1ICA = 265 rds Cal .50 linked, 2AP M2, 2INC M1, 1TR M1
T1ICC = 265 rds Cal .50 linked, 2AP, 2INC, 1TR
T1ICE = 265 rds Cal .50 linked, 4AP M2, 1TR M1
T1ICW = 240 rds Cal .50 linked, AP M2
T1IDC = 350 rds Cal .50 carton, API M8
T1IDD = 350 rds Cal .50 carton, API M8
T1IGD = 265 rds Cal. 50 linked, 4xBall M2, 1xTR M1
T1IGR = 240 rds Cal .50 linked, Ball M2
T1IIH = 265 rds Cal .50 linked, 1API M8, 1INC M1, 1API M8, 1INC M1, 1TR M10
T1IIN = 265 rds Cal .50 linked, 1API M8, 1INC M1, 1API M8, 1INC M1, 1API-T M20
T1IIW = 265 rds Cal .50 linked, 4API M8, 1API-T M20
T1IKC = 240 rds Cal .50 carton, INC M1
T1IPB = 350 rds Cal. 50 carton, TR M1
T1JAA = 265 rds Cal .50 linked, Defective TR M1
T1VGC = 350 rds Cal .50 carton, Dummy M2

I'm pretty sure there are a couple of typos in the source material incorporated in the list, but until I find a copy of SB 9-AMM 5 I don't know which they are.

Theoretically, the 5-character AIC breaks down as follows:
1: Supply Catalog designation section, in this case T: Small Arms Ammunition
2: Sub-section of above, in this case 1: Ammunition for Rifle, Carbine, and Automatic guns
3: Caliber, I for .50 Cal. ammunition
4: Projectile type(s)
5: Packaging method