Talk:Accessibility and ARIA

Last Paragraph Split into More Easily Digestible Chunks?

The aria-live attribute is the primary determination for the order of presentation of changes to live regions. ARIA describes live regions in terms of "politeness levels". Regions specified as polite will notify users of updates, but do not generally interrupt the current task. ARIA's assertive value is used when the update needs to be communicated to the user more urgently; for example, warning or error messages in a form that performs immediate validation for each form field.

Politeness levels are essentially an ordering mechanism for updates and serve as a strong suggestion to the user agent or assistive technology. The value may be overridden by the user agent, assistive technology, or user. Since different users have different needs, it is up to the user to tweak his or her assistive technology's response to a live region with a certain politeness level from the commonly defined baseline.

Implementations must also consider the default level of politeness in a role when the aria-live attribute is not set in the ancestor chain (for example, log (ref 6) changes are polite by default). Items which are assertive should be presented immediately, followed by polite items. An assistive technology is thus able to implement increasing and decreasing levels of granularity so that the user can exercise control over queues, interruptions and dynamic updates, which -- without ARIA bindings -- would be imperceptible to the user of assistive technology.