code: function( xpath, contextNode )
  		{
  			var baseXml = this.baseXml;
  
  			if ( contextNode || ( contextNode = baseXml ) )
  			{
  				if ( CKEDITOR.env.ie || contextNode.selectSingleNode )	// IE
  					return contextNode.selectSingleNode( xpath );
  				else if ( baseXml.evaluate )							// Others
  				{
  					var result = baseXml.evaluate( xpath, contextNode, null, 9, null);
  					return ( result && result.singleNodeValue ) || null;
  				}
  			}
  
  			return null;
  		}
docs: Get a single node from the XML document, based on a XPath query.
  @param {String} xpath The XPath query to execute.
  @param {Object} [contextNode] The XML DOM node to be used as the context
  for the XPath query. The document root is used by default.
  @returns {Object} A XML node element or null if the query has no results.
  @example
  // Create the XML instance.
  var xml = new CKEDITOR.xml( '<list><item id="test1" /><item id="test2" /></list>' );
  // Get the first <item> node.
  var itemNode = <b>xml.selectSingleNode( 'list/item' )</b>;
  // Alert "item".
  alert( itemNode.nodeName );