ActionScripting Basics: Expert Mode and Normal Mode
From Adrien-Luc Sanders, former About.com Guide
Your Flash Actions pane has two modes in which you can work your scripts: Normal Mode, and Expert Mode. Normal Mode, as the name so obviously implies, is the default way that Flash will let you browse and add scripts. Normal Mode will not allow you to type parameters into your scripts freely, or make unrestricted edits; instead it automatically populates the basic script for you, and gives you a panel of options where you can type in names or numbers for specific parameters, and check off specific options. While this can prevent you from making certain mistakes, it can also be a bit restrictive.