In the Dallas/Fort Worth Area there are some codes that almost all police and fire departments use including&
The standard Ten-Codes (10-4, 10-9, etc.)
Code 1 Non-emergency Response
Code 2 Urgent Response (sometimes with lights and sirens as necessary)
Code 3 Emergency Response with Lights and Sirens.
Many cities share the same radio codes, but some have unique codes. Here are codes and other information for a few cities that I have. More and more departments are going to "plain text" or "plain English" to meet interoperablity funding requirements.