I understood that what you provided can be implemented very simply, but I still like to try to understand what's happening and how it works--just to learn or if I want to make changes.
Keep in mind, I'm trying to institute a solution based on my current approach, but maybe there's a much smarter way of handling keeping users from editing data that involves locking the whole form and always forcing them to go into add mode (Data Entry = Yes or creating a modal form to signal the user is in New Record mode) or edit mode (Me.AllowEdits = false/true). I just haven't seen enough of how programmers approach these types of UI issues to learn how to implement what I may prefer.