def process_param(self):
        """ Reads and processes RETURNVALUE stream.

        This stream is used to send OUTPUT parameters from RPC to client.
        Stream format url: http://msdn.microsoft.com/en-us/library/dd303881.aspx
        """
        self.log_response_message('got RETURNVALUE message')
        r = self._reader
        if tds_base.IS_TDS72_PLUS(self):
            ordinal = r.get_usmallint()
        else:
            r.get_usmallint()  # ignore size
            ordinal = self._out_params_indexes[self.return_value_index]
        name = r.read_ucs2(r.get_byte())
        r.get_byte()  # 1 - OUTPUT of sp, 2 - result of udf
        param = tds_base.Column()
        param.column_name = name
        self.get_type_info(param)
        param.value = param.serializer.read(r)
        self.output_params[ordinal] = param
        self.return_value_index += 1
Reads and processes RETURNVALUE stream.

        This stream is used to send OUTPUT parameters from RPC to client.
        Stream format url: http://msdn.microsoft.com/en-us/library/dd303881.aspx