Hi [This is a resending due to issues with the email address I sent to. I apologize if you receive it in double] Looking into some timezone information I have the following interrogation, and I am unsure if my interpretation of the file is wrong, or if the rules are wrong... This comes from tzdata2009s, southamerica file The rules are # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Brazil 2008 max - Oct Sun>=15 0:00 1:00 S Rule Brazil 2008 2011 - Feb Sun>=15 0:00 0 - Rule Brazil 2012 only - Feb Sun>=22 0:00 0 - Rule Brazil 2013 2014 - Feb Sun>=15 0:00 0 - The Timezone # # east Amazonas (AM): Boca do Acre, Jutai, Manaus, Floriano Peixoto # The great circle line from Tabatinga to Porto Acre divides # east from west Amazonas. Zone America/Manaus -4:00:04 - LMT 1914 -4:00 Brazil AM%sT 1988 Sep 12 -4:00 - AMT 1993 Sep 28 -4:00 Brazil AM%sT 1994 Sep 22 -4:00 - AMT

From what I understand from the above, America/Manaus does not observe DST ever since Sep 22, 1994.

However, looking at the Microsoft Timezone definition [Dec 2009 update] for (GMT -4:00) Manaus [Central Brazilian Standard Time] the timezone observe DST from 3rd Saturday of October 23:59:59 to 3rd Saturday of February, 23:59:59. Also, another non-official site seems to imply the same: [http://www.icfsi2007.com/city_more.php will show Time Manaus Time Zone is 1 hour less than Brasilia, Sao Paulo or Rio de Janeiro Time Zone (GMT - 03:00), four hours behind of Greenwich Mean Time (GMT), except during the period between late October and the end of February, when daylight saving time is in force (GMT - 05:00 hours). ] So either a) I do not interpret the timezone rules properly for America/Manaus, and there is a DST being observed there. If so, please let me know how I should read the above rules/timezone information. b) Microsoft timezone is incorrect c) Olson data is incorrect d) The Microsoft timezone [(GMT -4:00) Manaus - Central Brazilian Standard Time] does not correspond to the Olson's America/Manaus timezone Your opinion would be appreciated Thanks -Alain Petit