# File lib/icalendar/tzinfo.rb, line 67
        def rrule 
            start = local_start.to_datetime
            # this is somewhat of a hack, but seems to work ok
            [sprintf(
                    "FREQ=YEARLY;BYMONTH=%d;BYDAY=%d%s",
                    start.month, 
                    ((start.day - 1)/ 7).to_i + 1,
                    start.strftime("%a").upcase[0,2]
                    )]
        end