title: Default value of xmlns?
body: <p>Consider we have the following xml document</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;Root&gt;
    &lt;Child /&gt;
  &lt;/Root&gt;
  </code></pre>
  
  <p>As you can see the <em>Root</em> does not have default namespace specification. Default namespace is specified with an attribute <em>xmlns</em>. </p>
  
  <p>The question is which is the default namespace of such xml document? </p>
  
  <p>If you post an answer could you please also include a reference where information was taken from, e.g. W3C.</p>