Part 2: Interlude: Ten-codes

The numbers that you see in the last update (and the title of this thread) are known as ten-codes (or eleven-codes for the less-common 11 variant). People using a single radio transmission channel have made use of these codes since the 1930's; they are primarily the domain of the police and CB operators, although with modern forms of communication they have been gradually disappearing over the last couple of decades.

Each code is shorthand for a particular incident, item, or idea. The initial "10" is actually there to attract attention and cause the receiving operator to adjust their set if necessary; the following number holds the actual data. The most well-known of these codes is probably "10-4" (transmission received), although you will still occasionally hear people ask "what's your 20?" (10-20 = location.)

In addition to shortening conversation (important if you are sharing a radio channel with a large number of people), the codes sometimes help obfuscate upsetting details (discussion of murders, robberies, etc). Officers can be assigned call numbers in the same way, to avoid having to identify them personally over the radio. (As you can see in this update, Sonny is 83-32.)

The meanings of the two codes used in the last update can probably be guessed from context, but just in case: 10-10 is off duty and 11-98 is a meeting. The use of these in a non-radio context is not unusual for police officers; as with any other professional, work jargon eventually makes its way into regular speech.