def cd_id_tag(self, for_box_id: bool = False) -> str:
        """
        Return (place-holder) credential definition identifier tag for current version of node protocol.
        At present, von_anchor always uses the tag of 'tag' if the protocol calls for one.

        :param for_box_id: whether to prefix a colon, if current protocol uses one, in constructing
            a cred def id or rev reg id.
        :return: cred def id tag
        """

        if for_box_id:
            return '' if self == Protocol.V_13 else ':tag'
        return 'tag'