code: public Expression locationPathPattern(int opPos)
            throws TransformerException
    {
  
      opPos = getFirstChildPos(opPos);
  
      return stepPattern(opPos, 0, null);
    }
docs: Compile a location match pattern unit expression.
  
  @param opPos The current position in the m_opMap array.
  
  @return reference to {@link org.apache.xpath.patterns.StepPattern} instance.
  
  @throws TransformerException if a error occurs creating the Expression.