Dunwoody PD callsigns?

[leicanthrope]

Wondering if there's anyone who's been listening to Dunwoody PD enough to have deciphered their callsigns?

In particular I'm trying to figure out what units use the "180" callsign, and what "zulu + [four digit number, probably badge]" indicates. Both are heard rarely enough that I haven't been able to accumulate much context.

 

[mjbjr]

Could Zulu mean the same as military? +12 hours?

 

[leicanthrope]

Could Zulu mean the same as military? +12 hours?

The two instances that I've got logged are both numbers between 0000-2400, so it's possible. I didn't record the time that those calls came in, but I remember it following the same format that they use for callsigns: i.e. starting a transmission with "zulu 1533 to Chatcom". Most of their day to day callsigns seem to be some combination of shift + beat + modifier for additional officers on a given beat. 232 would be the second officer working the "30" beat on the overnight shift, often being referred to as just 32 if they're sufficiently far away from shift change. It seems like most of the agencies in the county use a four digit identifier unique to an individual, although I'm not sure if that's strictly a badge number or something else. My gut feeling is that the "zulu" indicates some sort of status, like they're radioing in while off-duty or something along those lines.