I had a list of them that an officer gave me once, but i'm not sure what I did with it. I do remember these though.
Code 1 - Case Number
Code 10 - Emergency Response
Code 20 - Routine Response
I believe that codes 2, 3, 4 & 5 are disposition codes that indicate how a unit clears a call (no action taken, arrest made, etc...).
I sent you a private message with some extra information.
Also, when they say "Code 1 with number" it just means that they got the code 1 from their MDT (Mobile Data Terminal) and there is no need for the dispatcher to give the code over the radio.