</ul>

</p>

<p>The author SHOULD supply a <span>value</span> for <pref>aria-valuenow</pref> unless the value is indeterminate, in which case the author SHOULD omit the <pref>aria-valuenow</pref> attribute.

Authors SHOULD update this value when the visual progress indicator is updated. If the <code>progressbar</code> is describing the loading progress of a particular region of a page, the author SHOULD use <pref>aria-describedby</pref> to point to the status, and set the <sref>aria-busy</sref> attribute to <code>true</code> on the region until it is finished loading. It is not possible for the user to alter the value of a <code>progressbar</code> because it is always read-only.</p>

Authors SHOULD update this value when the visual progress indicator is updated. If the <code>progressbar</code> is describing the loading progress of a particular region of a page, authors SHOULD both use <pref>aria-describedby</pref> to reference the progressbar status, and set the <sref>aria-busy</sref> attribute to <code>true</code> on the region until it is finished loading. It is not possible for the user to alter the value of a <code>progressbar</code> because it is always read-only.</p>

<p class="note">Assistive technologies generally will render the value of <pref>aria-valuenow</pref> as a percent of a range between the value of <pref>aria-valuemin</pref> and <pref>aria-valuemax</pref>, unless <pref>aria-valuetext</pref> is specified.</p>

</div>

<table class="role-features">