@abc.abstractmethod<EOL><INDENT>def get_coordinate_types(self):<DEDENT>
return<EOL>
Gets the set of acceptable coordinate types.

        :return: the set of coordinate types
        :rtype: ``osid.type.Type``
        :raise: ``IllegalState`` -- syntax is not a ``COORDINATE or SPATIALUNIT``

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