El Dorado Sheriff Callsigns

[RRhodester]

I was wondering if anyone knows how the EDSO callsigns work for their patrol, sgts, K9s work?

 

[RRhodester]

So far I've heard it might be off of their beats? I've head a 10D, 21B, and a 22A. I assume the phonetic is the shift based on the time of day.