Restrict references to a custom app
Restrict references to a custom app to prevent the app's schema from being accessed by unauthorized files. For another file to access the app's schema and data, either the file must be authorized within the app or the user must enter valid credentials for the app.
You can specify that only accounts with the Full Access privilege set can create references to the custom app, ensuring that only app designers and administrators can reference the app. By default, newly created files have this option enabled.
In a multifile custom app, you must authorize each file that needs access to another file's schema.
See "Authorizing access to files" in FileMaker Pro Help.