Jesper is not on the time zone mailing list; be sure that any replies are directed appropriately. --ado -----Original Message----- From: Jesper Nørgaard [SMTP:jnorgard@Prodigy.Net.mx] Sent: Saturday, December 04, 1999 4:38 AM To: Olson, Arthur David (NCI) Subject: Possible error in Tonga time zone Hi, Arthur David Olson. I understand that you have done a lot of work on time zone rules to be used in programs, and I have been using the files in elsie.nci.nih.gov for my own PC program which you can download from http://www.cimmyt.cgiar.org/timezone/timezone.exe, which is an installation executable of 505 Kb. The program only works in 32-bit Windows, meaning Windows 95, Windows 98 and Windows NT 4.0 and upwards. The installation program can guide you through the process. The program is free to copy and use, by the way. I have noticed a change in Tonga which on http://www.timezoneconverter.com/tzchist.html is referred to as: "Tonga now observes DST from the first Saturday in October until the Third Saturday in April.(Tonga will now be the first country to observe the year 2000.) " However, in the australasia file I find the following current rule for Tonga: # Tonga # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Tonga 1999 max - Oct Sat>=1 2:00s 1:00 S Rule Tonga 2000 max - Apr Sun>=16 2:00s - - # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Pacific/Tongatapu 12:19:20 - LMT 1901 12:20 - TOT 1941 # Tonga Time 13:00 - TOT 1999 13:00 Tonga TO%sT In this case there is a discrepancy, since the third Sunday of April could fall on 15.th. of April, meaning that in that single case (which first happens 15.th. of April 2001) Tonga will leave Daylight Saving at Sunday the 22.nd. of April 2001 according to the above rule, but at Sunday the 15.th. of April 2001 according to the web page informal rule. My guess is that the rule really should state "Sun>=15" instead of "Sun>=16". Note that both rules will work correctly the year 2000, the problem arises first in 2001. Who is right? Hope you have a chance to look at my Time Zone Converter program by the way, and tell me what you think. A notabene is that I by mistake put my rule for Tonga leaving Daylight Saving as Last Saturday of April instead of Last Sunday. I will correct that as quickly as time permits ... Yours sincerely Jesper Nørgaard Welen, Jesper Nørgaard Email: jnorgard@df1.telmex.net.mx Programador/Analista CIMMYT - Centro Internacional de Mejoramiento de Maíz y Trigo Dirección: CIMMYT, Lisboa 27, 06600 Mexico, D.F. Tel.: +52 (5) 7267541 ext. 1374 Fax: +52 (5) 7267558 Tel. Casa: 53-10-05-95 ó 53-10-97-78 CIMMYT home page: http://www.cimmyt.mx