Revision 1015719 of itemid

<h2 id="Summary">Summary</h2>

<p>The <strong>Itemid </strong>attribute is the unique, global identifier of an item.</p>

<p>Itemid attributes can only be specified on elements that&nbsp; have both <strong>itemscope </strong>and <strong>itemtype </strong>attributes. Also, the itemid can only be specified on elements with an itemscope attribute whose corresponding itemtype refers to or defines a vocabulary that supports global identifiers.</p>

<p>An itemtype's vocabulary will give the exact meaning of a global identifier defined within the vocabulary. The vocabulary will define whether several items with the same global identifier can co-exist and, if they are allowed, how items with the same identifier are handled.</p>

<p class="note"><strong>Note:</strong> The Whatwg.org definition of an itemid says that it must be a URL. This does not seem to be the case as the example below shows. Rather the defacto definition is that an itemid is a unique identifier, so a URN is appropriate. This inconsistency no doubt reflects the incomplete nature of the Microdata specification.</p>

<h2 id="sEditExample"><a class="button section-edit only-icon" href="https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-alternates$edit#Example"><span>sEdit</span></a>Example</h2>

<h3 id="HTML">HTML</h3>

<pre class="brush: html">
&lt;dl itemscope
    itemtype="https://vocab.example.net/book"
    itemid="urn:isbn:0-330-34032-8"&gt;
&lt;dt&gt;Title &lt;dd itemprop="title"&gt;The Reality Dysfunction
&lt;dt&gt;Author &lt;dd itemprop="author"&gt;Peter F. Hamilton
&lt;dt&gt;Publication date
&lt;dd&gt;&lt;time itemprop="pubdate" datetime="1996-01-26"&gt;26 January 1996&lt;/time&gt; &lt;/dl&gt;</pre>

<h3 id="Structured_data">Structured data</h3>

<table class="standard-table">
 <tbody>
  <tr>
   <td colspan="1" rowspan="14">itemscope</td>
   <td>itemtype: itemid</td>
   <td colspan="2" rowspan="1">
    <div class="jyrRxf-eEDwDf jcd3Mb IZ65Hb-hUbt4d"><span>https://vocab.example.net/book</span>: urn:isbn:0-330-34032-8</div>
   </td>
  </tr>
  <tr>
   <td>itemprop</td>
   <td><span>title</span></td>
   <td><span>The Reality Dysfunction</span></td>
  </tr>
  <tr>
   <td>itemprop</td>
   <td><span>author</span></td>
   <td>
    <div class="jyrRxf-eEDwDf jcd3Mb"><span>Peter F. Hamilton</span></div>
   </td>
  </tr>
  <tr>
   <td>itemprop</td>
   <td><span>pubdate</span></td>
   <td><span>1996-01-26</span></td>
  </tr>
 </tbody>
</table>

<h3 id="Result">Result</h3>

<p>{{ EmbedLiveSample('HTML', '', '', '', 'Web/HTML/Global_attributes/itemid') }}</p>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table" style="height:105px; width:490px">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td><a href="https://html.spec.whatwg.org/multipage/microdata.html#attr-itemid">itemid</a></td>
   <td>WG Note - No longer being actively developed</td>
  </tr>
 </tbody>
</table>