@abc.abstractmethod<EOL><INDENT>def get_root_repository_ids(self):<DEDENT>
return<EOL>
Gets the root repository ``Ids`` in this hierarchy.

        :return: the root repository ``Ids``
        :rtype: ``osid.id.IdList``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

        *compliance: mandatory -- This method must be implemented.*