ICal recurrence
YEARLY
- http://tools.ietf.org/html/rfc5545 - Page 127
DTSTART;TZID=America/New_York:19970610T090000 RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7 ... Note: Since none of the BYDAY, BYMONTHDAY, or BYYEARDAY components are specified, the day is gotten from "DTSTART".
BYMONTHDAY implied.