def port_uri_segment(self):
        """
        :term:`string`: Adapter type specific URI segment for adapter port
        URIs, or the empty string ('') for adapters without ports.

        For example, 'network-ports' for a network adapter.
        """
        if self._port_uri_segment is None:
            family = self.get_property('adapter-family')
            try:
                self._port_uri_segment = self.port_uri_segment_by_family[
                    family]
            except KeyError:
                self._port_uri_segment = ''
        return self._port_uri_segment