I think your last interpretation finally got it right, this is what the DOT says. But I think they goofed up something when they wrote the DOT. The effect is that Indiana goes from GMT-5 to GMT-6 during one hour, and then to GMT-5 again one hour later??! In reality, I'm sure what they wanted to do is to keep Indiana on GMT-5 and on Eastern time until Central timezone shifts to Daylight Saving, and then define that point in time to be the shift in timezone. Then nobody in Indiana has to change wall clock in spring, until autumn when CDT shifts back to CST. I'll bet you no matter what official documents have been issued they won't shift the wall clock one hour behind just to shift it one hour ahead, an hour later. In effect at 2:59:59 EST they will shift to 3:00:00 CDT without any wall clock change. So the DOT text should have read "The effective *time* of this rule is 2:00 a.m. CST Sunday, April 2, 2006, which is the changeover *time* from Central Standard Time to Central Daylight Saving Time" ... or they could have used "3:00 a.m. EST" to the same effect. The rule should in tz-database format would then be -5:00 - EST 2006 Apr 2 3:00 -6:00 US C%sT In short, Indiana is on Eastern time until 3:00, and from then they are on Central (Daylight) time. By the way I don't think the time 2:00:00 CDT exists for that date (from an earlier mail), even for any place in the world - but that is maybe more of a philosophical problem. 2:00:00 CST and 3:00:00 CDT would exist (at least the latter) because they are in fact, the same. Jesper Nørgaard Welen -----Original Message----- From: Deborah Goldsmith [mailto:goldsmit@apple.com] Sent: Thursday, January 19, 2006 16:33 To: tz@lecserver.nci.nih.gov Subject: Re: DOT issues final ruling on Indiana time zones Sorry for the spam; I swear this is the last message. If I still have it wrong, I'll let someone else straighten it out. :-) In America/Indiana/Knox, on April 2, 2006: 1:59:59 EST is followed by 1:00:00 CST (because this location switches to Central Time at that moment, and it's Standard Time in that zone) 1:59:59 CST is followed by 3:00:00 CDT (the normal DST transition) It doesn't happen in one step; if it went from 1:59:59 to 3:00:00, it would be on EDT, not CDT. If it went from 1:59:59 to 2:00:00, then Knox would be on CDT an hour before the rest of its time zone. Now, that actually makes sense (clocks wouldn't have to change), but it's not what the DOT ruling says. It says "Starke county moves from ET to CT at the moment of the DST transition in the ET zone." Deborah Goldsmith Internationalization, Unicode liaison Apple Computer, Inc. goldsmit@apple.com