I believe I found an error in the summer-time rules for Uruguay. The latest version of the data (1997g) has the following as the last few lines of the Uruguay rule: Rule Uruguay 1989 only - Mar 12 0:00 0 - Rule Uruguay 1989 only - Oct 29 0:00 1:00 S Rule Uruguay 1990 1992 - Mar Sun>=1 0:00 0 - Rule Uruguay 1990 1991 - Oct Sun>=21 0:00 1:00 S Rule Uruguay 1992 1993 - Oct Sun>=15 0:00 1:00 S Rule Uruguay 1993 only - Feb 28 0:00 0 - I think the intent is to stop observing summer time after 1993 Feb 28. However, the effect is to keep summer time forever after 1993 Oct. I believe the next-to-last line should read: Rule Uruguay 1992 only - Oct Sun>=15 0:00 1:00 S That way, the change to standard time on 1993 Feb 28 is the last rule executed. On a personal note, I just want to thank you for going to all the trouble of compiling this vast repository of time zone information. I couldn't imagine trying to pull all this together myself. Thanks also for supplying it so freely to the Internet community.