&lt;li role="option" aria-setsize="16" <strong>aria-posinset="7"</strong>&gt; cantaloupes &lt;/li&gt;

&lt;li role="option" aria-setsize="16" <strong>aria-posinset="8"</strong>&gt; dates &lt;/li&gt;

&lt;/ul&gt;</pre>

<p>Authors MUST set the value for<pref>aria-posinset</pref> toan integer greater than or equal to 1, and less than or equal to the size of the set when that size is known.Authors SHOULD use <pref>aria-setsize</pref>.</p>

<p>Whenexposing <code>aria-posinset</code> on a <rref>menuitem</rref>, <rref>menuitemcheckbox</rref>, or <rref>menuitemradio</rref>, authors SHOULD set the value of <code>aria-posinset</code> with respect to the total number of items in the <rref>menu</rref>, excluding any separators.</p>

<p>When specifying<pref>aria-posinset</pref>, authors MUST specify a value that isan integer greater than or equal to 1, and less than or equal to the size of the set when that size is known.If authors specify <pref>aria-posinset</pref>, authors MUST also specify a value for <pref>aria-setsize</pref>.</p>

<p>Whenspecifying <code>aria-posinset</code> on a <rref>menuitem</rref>, <rref>menuitemcheckbox</rref>, or <rref>menuitemradio</rref>, authors SHOULD set the value of <code>aria-posinset</code> with respect to the total number of items in the <rref>menu</rref>, excluding any separators.</p>

</div>

<table class="property-features">

<caption>Characteristics:</caption>

<div class="property-description">

<p>Defines the number of items in the current set of listitems or treeitems. Not required if all elements in the set are present in the <abbr title="Document Object Model">DOM</abbr>. See related <pref>aria-posinset</pref>.</p>

<p>This <a>property</a> is marked on the members of a set, not the container element that collects the members of the set. To orient the user by saying an element is "item X out of Y," the <a>assistive technologies</a> would use X equal to the <pref>aria-posinset</pref> <a>attribute</a> and Y equal to the <code>aria-setsize</code> attribute.</p>

<p>If all items in a set are present in the document structure, it is not necessary to set thisproperty, as the <a>user agent</a> can automatically calculate theset size andposition foreach item. However, ifonly a portion of the setispresent in the document structure at a given moment (in order to reduce document size),thisproperty is neededto provide an explicit indication ofset size.</p>

<p>Authors MUST set the value of<code>aria-setsize</code> to an integer equal to the number of items in the set. If the total number of items is unknown, authors SHOULD set the value of <code>aria-setsize</code> to <code>-1</code>.</p>

<p>Whenexposing <code>aria-setsize</code> on a <rref>menuitem</rref>, <rref>menuitemcheckbox</rref>, or <rref>menuitemradio</rref>, authors SHOULD set the value of <code>aria-setsize</code> based on the total number of items in the <rref>menu</rref>, excluding any separators.</p>

<p>If all itemsup to the current itemin a set are present in the document structure, it is not necessary to set this<a>attribute</a>, as the <a>user agent</a> can automatically calculate the position forthese items. However, ifall previous items in the setare notpresent in the document structure at a given moment, the author MUST setthis<a>attribute</a>to provide an explicit indication ofan element's position.</p>

<p>When specifying<code>aria-setsize</code>, authors MUST set the value to an integer equal to the number of items in the set. If the total number of items is unknown, authors SHOULD set the value of <code>aria-setsize</code> to <code>-1</code>.</p>

<p>Whenspecifying <code>aria-setsize</code> on a <rref>menuitem</rref>, <rref>menuitemcheckbox</rref>, or <rref>menuitemradio</rref>, authors SHOULD set the value of <code>aria-setsize</code> based on the total number of items in the <rref>menu</rref>, excluding any separators.</p>

<p>The following example shows items 5 through 8 in a set of 16.</p>

<pre class="example highlight">&lt;h2 id="label_fruit"&gt; Available Fruit &lt;/h2&gt;

&lt;ul role="listbox" aria-labelledby="label_fruit"&gt;