Yes, I did check it (actually I just checked everything thoroughly). I found all of the information for Fire/Rescue but none for police as far as how their units are identified over the radio.
Maryland State Police has talkgroups on the County system. The radios are programmed so that County officers can come up on the MSP TG and MSP officers can come up on MCPD TGs. Park officers can come up on MCPD TGs. There are a bunch of other police agencies with TGs on the County system, but I don't recall hearing their officers on County PD TGs (for example, NIST, NIH, Takoma Pk, and Maryland Transportation Authority).Thanks that is what I was looking for?
Do you know if any of the other cities other then Chevy Chase come up on MCPD radios? How about Sheriff's (I think they just call themselves Sheriff XXX though), County Security or MNCRPP (Maryland/National Capital Region Park Police)