    from Attr import Attr

    class AnyDateTimeAttr(Attr):

        def __init__(self, attr):
            Attr.__init__(self, attr)

    class DateTimeAttr(AnyDateTimeAttr):

        def __init__(self, attr):
            Attr.__init__(self, attr)

    class DateAttr(AnyDateTimeAttr):

        def __init__(self, attr):
            Attr.__init__(self, attr)

    class TimeAttr(AnyDateTimeAttr):

        def __init__(self, attr):
            Attr.__init__(self, attr)

    # @@ 2000-10-13 ce: complete