It indicates which squad a unit is from, how many officers are in the vehicle, and what shift they're working. From the Southwest Frequency Directory, 10th Edition (2009).
1st Squad, One Officer in vehicle: A 1st shift, F 2nd shift, J 3rd shift
2nd Squad, One Officer: B 1st shift, G 2nd shift, K 3rd shift
Second unit in a beat, 1 Officer: D 1st shift, H 2nd shift, L 3rd shift
(Cactus Park beat 912. The first 1 officer unit from the first squad working the first shift would be 912A. The first 1 officer unit from the second squad working the first shift would be 912B. The second 1 officer unit from the first squad working the first shift would be 912D.)
1st Squad, 2 Officers in vehicle: E 1st shift, I 2nd shift, M 3rd shift (1st Officer 912E, 2nd officer 912EA.)
Second Two Officer unit: O (Ocean? Oscar?) in all shifts
(Cactus Park, beat 912. A two officer unit in beat 912 day shift would be 912D. The second two officer unit would be 912O.)
(The actual number of officers in any given beat will depend on crime levels, and how many officers are actually available to be put in any given beat. You may never actually hear 912A, 912B, 912D, 912E/912EA, and 912O/912OA all at the same time. And then there's 912R, and 912T/912TA, as well as Area 91, and 91A. See below.)
Civillian Motorist Assist: Charles in all shifts
Reserve Officer: Robert in all shifts
The Curfew Wagon is a W suffix in all shifts. Wagon as a prefix is the jail wagon.
Gang unit/Street Crimes: Zebra in all shifts
Training Officer: T in all shifts (912T is the training officer, 912TA is the rookie officer)
Area 91: Lieutenant in Area 91, covers beats 911, 912, 913, 914, 915, in the south area of the Cactus Park precinct.
91A, first shift Sergeant in Area 91, covers beats 911, 912, 913, 914, 915.
Patrol 91: Night Lieutenant, responsible for entire Cactus Park precinct overnight.
John
Peoria
