Revision 1015685 of itemid

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

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

<p>The itemid attribute 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 defines a vocabulary that supports global identifiers.</p>

<p>The exact meaning of a global identifier is determined by the itemtype vocabulary.The vocabulary can define whether multiple items with the same global identifier are allowed, and what the processing rules for that vocabulary are with respect to handling the case of multiple items with the same ID.</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>