title: Select all elements that does not exist in another node with XSLT
body: <p>I want to select all elements that does not exist in another node.</p>
  
  <pre><code>&lt;root&gt;
    &lt;users&gt;
      &lt;array&gt;
        &lt;name&gt;John&lt;/name&gt;
        &lt;age&gt;30&lt;/age&gt;
      &lt;/array&gt;
      &lt;array&gt;
        &lt;name&gt;Joe&lt;/name&gt;
        &lt;age&gt;30&lt;/age&gt;
      &lt;/array&gt;
      &lt;array&gt;
        &lt;name&gt;Lou&lt;/name&gt;
        &lt;age&gt;30&lt;/age&gt;
      &lt;/array&gt;
    &lt;/users&gt;
    &lt;selected_users&gt;
      &lt;name&gt;Joe&lt;/name&gt;
      &lt;age&gt;30&lt;/age&gt;
    &lt;/selected_users&gt;
  &lt;/root&gt;
  </code></pre>
  
  <p>So what I want from this list is John and Lou since their not listed under the selected users node..</p>