Baylink says: This is a (trimmed and slightly modified) version of the APCO 10-code list, tuned for the sort of communications I conduct via Nextel; you might find it useful as well.
Each of these 10-codes can be used as a statment or a question; the meaning is fundamentally the same whether the context is "I am ...", "You should ..." or "Are you ...?"
- 10-1 - Receiving poorly
- 10-2 - Receiving well
- 10-4 - Message received OK -- note that this does *not* mean "wilco", only "roger". It also doesn't mean "affirmative". :-)
- 10-6 - Busy -- often followed by the number of minutes you'll be tied up
- 10-7 - (going) out of service
- 10-8 - In service; idle or available
- 10-9 - Please repeat message
- 10-10 - Transmission complete
- 10-12 - Officials or Visitors present (ie: watch what you say and how)
- 10-13 - Anyone besides me is around -- I am not alone (for messages even more private than 10-12)
- 10-30 - Against the rules
- 10-33 - Emergency situation or message
- 10-36 - Correct time
- 10-51 - Enroute
- 10-58 - Eating/meal
- 10-94 - Send backup (for which having a non-obvious code might be more useful than you'd think)
- 10-98 - Completed assignment/arrived at destination
- 10-99 - Unable to copy; try later
One non-ten-code is "Channel 2", as in "go to Channel 2". This is a request that the person at the other end switch their radio from normal mode (using the loud or 'high' speaker) to private or 'handset' mode, so that others who might be around them don't hear the transmission; the customary responses are "Channel 2" or "negative 10-12".
You might also inquire "10-12?", to which the appropriate response might be "affirmative", "negative", or "Channel 2", as indicated.