At some point in the development of your database application, you will need to use the debugger. As soon as the debugger is invoked, 4D will create a copy of the current method and use this copy to step through it. If you realize your errors or simply need to make some changes to the current method, you can press the "Edit" button, edit the method, and save the method. The copy that the debugger is working on is not going to be updated until the debugger calls the original method again.