This article in particular is good about describing this: https://web.archive.org/web/20140221080916/http://www.cstdbill.com/tzdb/tz-h... It's too bad that we have to use archive.org to get at this seemingly fundamental doc. Any way we could host it along side tz-link.html in the repo? Date: Mon, 19 Oct 2015 13:55:24 -0400 From: tim@timtimeonline.com To: Jim.Marvel@honeywell.com CC: tz@iana.org Subject: Re: [tz] 2015g: Is the 1:00 under Pacific/Norfolk "Rules" a typo? On 19 October 2015 at 10:06, Marvel, Jim (CPCOE) <Jim.Marvel@honeywell.com> wrote: Hello, Is the 1:00 under Pacific/Norfolk "Rules" a typo? No; the lines 11:30 - NFT 1974 Oct 27 02:00 # Norfolk T. 11:30 1:00 NFST 1975 Mar 2 02:00 indicate that, between 1974-10-27 02:00 local and 1975-03-02 02:00 local, Pacific/Norfolk observed Daylight Saving in the amount of one hour on top of its normal offset of UTC+11:30; that is, the area was on UTC+12:30 for that period. This was introduced recently and is documented accordingly: # From Paul Eggert (2015-09-23): # Transitions before 2015 are from timeanddate.com, which consulted # the Norfolk Island Museum and the Australian Bureau of Meteorology's # Norfolk Island station, and found no record of Norfolk observing DST # other than in 1974/5. See: # http://www.timeanddate.com/time/australia/norfolk-island.html-- Tim Parenti