def get_ipv4fs_table(self):
        """Returns global IPv4 Flow Specification table.

        Creates the table if it does not exist.
        """
        ipv4fs_table = self._global_tables.get(RF_IPv4_FLOWSPEC)
        # Lazy initialization of the table.
        if not ipv4fs_table:
            ipv4fs_table = IPv4FlowSpecTable(self._core_service,
                                             self._signal_bus)
            self._global_tables[RF_IPv4_FLOWSPEC] = ipv4fs_table
            self._tables[(None, RF_IPv4_FLOWSPEC)] = ipv4fs_table

        return ipv4fs_table
Returns global IPv4 Flow Specification table.

        Creates the table if it does not exist.