code: public Expression locationPath(int opPos) throws TransformerException
    {
      locPathDepth++;
      try
      {
        DTMIterator iter = WalkerFactory.newDTMIterator(this, opPos, (locPathDepth == 0));
        return (Expression)iter; // cast OK, I guess.
      }
      finally
      {
        locPathDepth--;
      }
    }
docs: Compile a location path.  The LocPathIterator itself may create
  {@link org.apache.xpath.axes.AxesWalker} children.
  
  @param opPos The current position in the m_opMap array.
  
  @return reference to {@link org.apache.xpath.axes.LocPathIterator} instance.
  
  @throws TransformerException if a error occurs creating the Expression.