title: Sharepoint caml update batch: how pass null value
body: <p>When I need to update some values in the SharePoint list I create the caml-batch like this:</p>
  
  <pre><code>&lt;Batch ListVersion="1" OnError="Continue"&gt;
  &lt;Method Cmd="Update" ID="1"&gt;
      &lt;Field Name="ID"&gt;123&lt;/Field&gt;
      &lt;Field Name="MyField"&gt;my value&lt;/Field&gt;
  &lt;/Method&gt;&lt;/Batch&gt;
  </code></pre>
  
  <p>How can I pass the null-value to such a batch?</p>