There's lots of interesting information on the site below:
https://dps.mn.gov/divisions/ecn/programs/armer/Pages/armer-standards.aspx
You may also find Anoka County information at:
Anoka County (MN) - The RadioReference Wiki
The term "Radio Unit IDs" can mean a couple of things. One thing is sort of like an internal electronic serial number that is unique to each radio. When the user keys the radio, this number is transmitted as part of the signal. It may show up on the dispatch console (and other equipment such as Uniden XT scanners) as something like "1800101". (That's one version of what a Radio ID Number can mean).
Different areas have a schema to break down what all this means. In my part of the world the first character translates into the discipline, with 1 being fire service. The next four numbers are associated with the given unit. The 6th digit means portable radio. The last digit is which portable. Putting this all together, 1800101 means "a fire radio associated with unit 8001 which is portable radio 1" (1800102 would mean fire radio 8001 portable radio #2).
Radio ID can also mean a "call sign" or "call number" associated with the user. An example is "Car 8001". In my area the "80" part translates into "Okolona Fire Department" and the "01" part means "fire chief".