Otherwise, if a user agent provides an implicit <sref>aria-selected</sref> value for an <rref>option</rref>, the value SHOULD be <code>false</code>.

</p>

<p>

Authors MAY indicate selection for <rref>option</rref> elements using either <sref>aria-selected</sref> or <sref>aria-checked</sref>.

Some user interfaces indicate selection with <sref>aria-selected</sref> in single-select list boxes and with <sref>aria-checked</sref> in multi-select list boxes.

Authors SHOULD indicate selection for <rref>option</rref> elements using one of the following:

</p>

<ul>

<li>An <sref>aria-selected</sref> value of <code>true</code> on the selected option within a single-select <rref>listbox</rref>, and optionally <sref>aria-selected</sref> values of <code>false</code> on unselected options.</li>

<li>Either <sref>aria-selected</sref> or <sref>aria-checked</sref> on all options within a multi-select <rref>listbox</rref>, with a value of <code>true</code> on selected options, and a value of <code>false</code> on unselected options.</li>

</ul>

<p>

Authors SHOULD NOT specify both <sref>aria-selected</sref> and <sref>aria-checked</sref> on <rref>option</rref> elements contained by the same <rref>listbox</rref> except in the extremely rare circumstances where all the following conditions are met:

</p>

<ul>