def moveObjectsByDelta(ids, delta, subset_ids=None):
    """ Move specified sub-objects by delta.

        If delta is higher than the possible maximum, objects will be moved to
        the bottom. If delta is lower than the possible minimum, objects will
        be moved to the top.

        If subset_ids is not None, delta will be interpreted relative to the
        subset specified by a sequence of ids. The position of objects that
        are not part of this subset will not be changed.

        The order of the objects specified by ids will always be preserved. So
        if you don't want to change their original order, make sure the order
        of ids corresponds to their original order.

        If an object with id doesn't exist an error will be raised.

        Permission -- Manage properties

        Returns -- Number of moved sub-objects
        """
