title: XPath to get the element with the highest ID
body: <p>XML Source:</p>
  
  <pre><code>&lt;documents&gt;
      &lt;document&gt;
          &lt;id&gt;3&lt;/id&gt;
      &lt;/document&gt;
      &lt;document&gt;
          &lt;id&gt;7&lt;/id&gt;
      &lt;/document&gt;
      &lt;document&gt;
          &lt;id&gt;1&lt;/id&gt;
      &lt;/document&gt;
  &lt;/documents&gt;
  </code></pre>
  
  <p>I need the <strong>document-element with the highest value in its id-element</strong> (so <code>&lt;document&gt;&lt;id&gt;7&lt;/id&gt;&lt;/document&gt;</code> in the example). I can't change the C# code, it is <code>XMLDocument.SelectSingleNode(...)</code>, I only can modify the XPath used.</p>
  
  <p>Is there something like <code>documents/document[id=max(id)]</code> or like <code>order by id descending</code> to get it?</p>