code: public DTMIterator asIteratorRaw(XPathContext xctxt, int contextNode)
            throws javax.xml.transform.TransformerException
    {
  
      try
      {
        xctxt.pushCurrentNodeAndExpression(contextNode, contextNode);
  
        XNodeSet nodeset = (XNodeSet)execute(xctxt);
        return nodeset.iterRaw();
      }
      finally
      {
        xctxt.popCurrentNodeAndExpression();
      }
    }
docs: Given an select expression and a context, evaluate the XPath
  and return the resulting iterator, but do not clone.
  
  @param xctxt The execution context.
  @param contextNode The node that "." expresses.
  
  
  @return A valid DTMIterator.
  @throws TransformerException thrown if the active ProblemListener decides
  the error condition is severe enough to halt processing.
  
  @throws javax.xml.transform.TransformerException
  @xsl.usage experimental