code: public void startAdded() throws DiffException {
          Element tmp = doc.createElementNS(XML_URI, "added");
          currentNode.appendChild(tmp);
          currentNode = tmp;
      }
docs: Start the added section.
  This opens the &lt;added&gt; tag.
  
  @throws DiffException when there is an underlying exception, e.g.
  writing to a file caused an IOException