If you can generate Hebrew-calendar dates, that will do it. It's always either the 4th, 6th, 7th, or 9th of Tishri (whichever of those four falls on a Sunday). In the language of tzData, it's Sun>=3 (just on a month that the tz code doesn't handle). J Andrew Lipscomb, CPA*ABV, ASA Decosimo Advisory Services 900 Tallan Building 2 Union Square Chattanooga, TN 37402 423.756.7100 Fax 423.266.6671 www.decosimo.com/advisory -----Original Message----- From: Vilas Khare (vkhare) [mailto:vkhare@cisco.com] Sent: Friday 07 January 2011 18:36 To: tz@lecserver.nci.nih.gov Subject: Timezone for Asia/Jerusalem For Asia/Jerusalem (URL below) time zone -- DST begin date seems to be consistently on the 'First Friday' following March 26th every year. If March 26 falls on Friday then DST begins on that Friday. But I fail to see any pattern in DST end date. Currently, we have been defining new time zone rule every year for Asia/Jerusalem in our metadata but want to know if we can fit in some generic pattern to avoid maintenance. http://www.timeanddate.com/worldclock/timezone.html?n=110 Any suggestions ? Vilas --