# File lib/icalendar/tzinfo.rb, line 78
        def dtstart
            local_start.to_datetime.strftime("%Y%m%dT%H%M%S")
        end

# File lib/icalendar/tzinfo.rb, line 57
        def offset_from
            a = previous_offset.utc_total_offset
            sprintf("%2.2d%2.2d", (a / 3600).to_i, ((a / 60) % 60).to_i)
        end

# File lib/icalendar/tzinfo.rb, line 62
        def offset_to
            a = offset.utc_total_offset
            sprintf("%2.2d%2.2d", (a / 3600).to_i, ((a / 60) % 60).to_i)
        end

# 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