title: XDocument.Descendants(itemName) - Problems finding qualified name
body: <p>I'm trying to read a XML-RSS-Feed from a website. Therefore I use a async download and create a <code>XDocument</code> with the <code>XDocument.Parse()</code> Method.</p>
  
  <p>The Document intends to be very simple, like this:</p>
  
  <pre><code>&lt;root&gt;
    &lt;someAttribute&gt;&lt;/SomeAttribute&gt;
    &lt;item&gt;...&lt;/item&gt;
    &lt;item&gt;...&lt;/item&gt;
  &lt;/root&gt;
  </code></pre>
  
  <p>Now I want to read out all the items. Therefore I tried:</p>
  
  <pre><code>foreach (XElement NewsEntry in xDocument.Descendants("item"))
  </code></pre>
  
  <p>but this doesn't work. So I found a post in this board to use the qualified name, because there are some namespaces defined in the root element:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="ISO-8859-1" ?&gt; 
  &lt;rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:sy="http://purl.org/rss/1.0/modules/syndication/" xmlns="http://purl.org/rss/1.0/"&gt;
  </code></pre>
  
  <p>well, I tried all 3 available namespaces - nothing worked for me:</p>
  
  <pre><code>XName itemName = XName.Get("item", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
  XName itemName2 = XName.Get("item", "http://purl.org/dc/elements/1.1/");
  XName itemName3 = XName.Get("item", "http://purl.org/rss/1.0/modules/syndication/");
  </code></pre>
  
  <p>Any help would be appreciated.
  (Usually I'm doing the XML-Analysis with Regex - but this time I'm developing for a mobile device, and therefore need to care about performance.)</p>