Going into interesting territory. An explanation of the current programming language used, ActionScript 3, is given along with how MXML translates to it and vice versa. It then shows the visual design and their controls, correlating it with the mxml source that shows up as you drag and drop controls on the design.
Found out what was up with the bindable tags that are appended to ActionScript variables. Bindable enables a variable to broadcast its content when updated, alerting the elements that listen for and display or use such content. By default ActionScript variables are not bindable and each and every one must be appended for all to be bindable. MXML variables (eg. mx:Number) are automatically bindable however.