What is keyboard shortcut Ctrl+F12 used for? Yes, that would be my Dynamics NAV technical interview question for you. If you spend at least a little bit time of doing development, hopefully, you are aware of function the View > Go To Definition.
And what a time-saver it is! While working in one codeunit, you can quickly jump to any other function (regardless, whether it is in different codeunit, or table), by clicking on the function which you want to check (for example, DateNotAllowed),
and then clicking View > Go To Definition (or obviously, if you love keyboard shortcuts, and you better would! just click Ctrl+F12).