title: Difference between / and /root-node
body: <p>My document looks like the following:</p>
  
  <pre><code>&lt;a&gt;
      whatever
  &lt;/a&gt;
  </code></pre>
  
  <p>If I run <code>/</code> or <code>/a</code> on the entire document is returned(at least effectively).
  If I run <code>/a/..</code> the entire document is returned.
  But <code>/..</code> returns an empty sequence 
  Considering  <code>/</code> and <code>/a</code> are returning the same node how come <code>/a/..</code> and <code>/..</code> are different?</p>