An initial 4A N2...?

[Jonathon Green]

The 'ten codes' are indeed jargon (another definition for which I would
suggest is professional or occupational slang). Though 10-4 does seem to
have moved into slang, as in

1990 Morgan _Homeboy_ 5: She was a big Ten Four for the rest of the evening
1996 P. Cornwell _Cause of Death_ (1997) 25: Everything ten-four?

where it means simply 'ready' and/or 'prepared.'

The current example de luxe of this kind of crossover is not a 10-Code but
'187', in legal terminology the California penal code for homicide and used
in rap/hip-hop to mean 1. a homicide; 2. (in weakened form) any type of
drama or crisis; 3. one who has been targeted for assassination.

Another such, though much less common, is '459': 1. a burglary; 2. to steal
(Calif. penal code section 459 dealing with burglary or intrusive behavior)

Jonathon Green