sp:id
 attribute.  Each XML element in the XML view available will
 be extended with this attribute.  The TagLibraryValidator
 can then use the attribute in one or more ValidationMessage
 objects.  The container then, in turn, can use these
 values to provide more precise information on the location
 of an error.
  
 <p>
 The actual prefix of the <code>id</code> attribute may or may not be 
 <code>jsp</code> but it will always map to the namespace
 <code>http://java.sun.com/JSP/Page</code>.  A TagLibraryVal