Allow the user to move the content focus to any enabled element in the viewport.
Allow configuration so that the content focus of a viewport only changes on explicit user request.
If the author has not specified a navigation order, allow at least forward sequential navigation, in document order, to each element in the set established by provision one of this checkpoint.
Sufficient techniques
To satisfy provision two of this checkpoint, configuration is preferred, but is not required if the content focus only ever changes on explicit user request.
Normative inclusions and exclusions
The user agent may also include disabled elements in the navigation order.