@abc.abstractmethod<EOL><INDENT>def register_for_entered_spatial_unit_for_resource(self, resource_id, spatial_unit):<DEDENT>
pass<EOL>
Register for notifications of an entered spatial unit.

        ``ResourcePositionReceiver.enteredSpatialUnit()`` is invoked
        when the specified resource appears in the specified spatial
        unit.

        :param resource_id: the ``Id`` of the ``Resource`` to monitor
        :type resource_id: ``osid.id.Id``
        :param spatial_unit: the ``SpatialUnit`` to monitor
        :type spatial_unit: ``osid.mapping.SpatialUnit``
        :raise: ``NullArgument`` -- ``resource_id`` or ``spatial_unit`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure
        :raise: ``Unsupported`` -- spatial unit not supported

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