01. Set up the error handler
At the top of the code for your procedure, the error handler is set up using On Error GoTo Proc_Err
02. Exit Code
After whatever your procedure does, a line label for the exit code (such as Proc_Exit: ) is used to signify what happens at the end of the procedure. This can be code to cleanup object variables, or simply code to gracefully exit.
03. Error Handling Code
After the exit code, a line label for the error handling code (such as Proc_Err: ) is used to begin what happens if there is an error.