The two aspects to tab indexing order are the tab order in which a user navigates through the web content and the order in which things are read by the screen reader, called the reading order.

Flash Player uses a tab index order from left to right and top to bottom. Customize both the tab and reading order by using the tabIndex property in ActionScript (in ActionScript, the tabIndex property is synonymous with the reading order).

Tab order

The order in which objects receive input focus when users press the Tab key. Use ActionScript to create the tab order, or if you have Adobe® Flash® CS3 Professional, use the Accessibility panel. The tab index that you assign in the Accessibility panel does not necessarily control the reading order.

Reading order

The order in which a screen reader reads information about the object. To create a reading order, use ActionScript to assign a tab index to every instance. Create a tab-order index for every accessible object, not just the focusable objects. For example, dynamic text must have tab indexes, even though a user cannot tab to dynamic text. If you do not create a tab index for every accessible object in a given frame, Flash Player ignores all tab indexes for that frame whenever a screen reader is present, and uses the default tab ordering instead.