A string that contains the value of the specified attribute; string.Empty if a matching attribute is not found, or if the System.Xml.XPath.XPathNavigator is not positioned on an element node.
The System.Xml.XPath.XPathNavigator must be positioned on an element node before calling the XPathNavigator.GetAttribute(string, string) method.
This method has no effect on the state of the System.Xml.XPath.XPathNavigator.