title: What assembly does XmlDocument live in, and how do I use it?
body: <p>I have the following code:</p>
  
  <pre><code>using System.Xml;
  namespace MyApp {
    public class Foo : IBar {
      public void SomeCallback(object sender, CallbackEventArgs e) {
        string s = e.Result;
        System.Xml.XmlDocument xml;  // &lt;-- Error CS0234.
        ...
  </code></pre>
  
  <p>This results in <code>error CS0234: The type or namespace name 'XmlDocument' does not exist in the namespace 'System.Xml' (are you missing an assembly reference?)</code></p>
  
  <p>I have verified that System.Xml is included under "References" in Solution Explorer.  It's listed as using 2.0.x.x, but that should be fine since the class <a href="http://msdn.microsoft.com/en-us/library/system.xml.xmldocument%28VS.80%29.aspx" rel="nofollow">allegedly existed</a> then?</p>
  
  <p>I'm not well versed in .net development, so I'm not sure how to troubleshoot this.</p>