The Hebrew calendar is tricky. Seven years in each nineteen-year cycle, an extra month is added. Furthermore, months can vary in number of days, from year to year.
Special care is needed for cases where
- The congregant knows only the Hebrew month and day, but not the year
- The Hebrew month is one of varying lengths, analogous to February 29th.
yahrzeit_demo from Norman Snyder on Vimeo.