From b980f1cac5121f702eb6b0cc679d960e8a275a3f Mon Sep 17 00:00:00 2001 From: Tim Parenti Date: Sat, 5 Dec 2020 13:39:09 -0500 Subject: Model Turks & Caicos time 2015-2018 as AST (Thanks to P Chan.) * NEWS: Mention this. * northamerica (America/Grand_Turk): Model the year-round observance of -04 in the Turks & Caicos Islands as AST from 2015-03 through 2018-03, to better match the legislation. This only affects the abbreviation and DST flag 2015-03-08/11-01. Expand commentary on slight discrepancy with the 2018-03-11 return to Eastern Time with US rules. --- NEWS | 7 +++++++ northamerica | 31 +++++++++++++++++++++++++++---- 2 files changed, 34 insertions(+), 4 deletions(-) diff --git a/NEWS b/NEWS index 2182c70..0937d8a 100644 --- a/NEWS +++ b/NEWS @@ -27,6 +27,13 @@ Unreleased, experimental changes Australia/Currie has been moved to the 'backward' file and its corrected data moved to the 'backzone' file. + Changes to past time zone abbreviations and DST flags + + To better match legislation in Turks and Caicos, the 2015 shift to + year-round observance of -04 is now modeled as AST throughout before + returning to Eastern Time with US DST in 2018, rather than as + maintaining EDT until 2015-11-01. (Thanks to P Chan.) + Release 2020d - 2020-10-21 11:24:13 -0700 diff --git a/northamerica b/northamerica index d8bb8f8..ddc5759 100644 --- a/northamerica +++ b/northamerica @@ -3727,7 +3727,7 @@ Zone America/Miquelon -3:44:40 - LMT 1911 May 15 # St Pierre # "Eastern Standard Times Begins 2007 # Clocks are set back one hour at 2:00 a.m. local Daylight Saving Time" # indicating that the normal ET rules are followed. -# + # From Paul Eggert (2014-08-19): # The 2014-08-13 Cabinet meeting decided to stay on UT -04 year-round. See: # http://tcweeklynews.com/daylight-savings-time-to-be-maintained-p5353-127.htm @@ -3742,19 +3742,42 @@ Zone America/Miquelon -3:44:40 - LMT 1911 May 15 # St Pierre # during the summer months and Standard Time, also known as Local # Time, during the winter months with effect from April 2018 ... # https://www.gov.uk/government/news/turks-and-caicos-post-cabinet-meeting-statement--3 -# # From Paul Eggert (2017-08-26): # The date of effect of the spring 2018 change appears to be March 11, # which makes more sense. See: Hamilton D. Time change back # by March 2018 for TCI. Magnetic Media. 2017-08-25. # http://magneticmediatv.com/2017/08/time-change-back-by-march-2018-for-tci/ # +# From P Chan (2020-11-27): +# Standard Time Declaration Order 2015 (L.N. 15/2015) +# http://online.fliphtml5.com/fizd/czin/#p=2 +# +# Standard Time Declaration Order 2017 (L.N. 31/2017) +# http://online.fliphtml5.com/fizd/dmcu/#p=2 +# +# From Tim Parenti (2020-12-05): +# Although L.N. 31/2017 reads that it "shall come into operation at 2:00 a.m. +# on 11th March 2018", a precise interpretation here poses some problems. The +# order states that "the standard time to be observed throughout the Turks and +# Caicos Islands shall be the same time zone as the Eastern United States of +# America" and further clarifies "[f]or the avoidance of doubt" that it +# "applies to the Eastern Standard Time as well as any changes thereto for +# Daylight Saving Time." However, as clocks in Turks and Caicos approached +# 02:00 -04, and thus the declared implementation time, it was still 01:00 EST +# (-05), as DST in the Eastern US would not start until an hour later. +# +# Since it is unlikely that those on the islands switched their clocks twice in +# the span of an hour, we assume instead that the adoption of EDT actually took +# effect once clocks in the Eastern US had sprung forward, from 03:00 -04. +# This discrepancy only affects the time zone abbreviation and DST flag for the +# intervening hour, not wall clock times, as -04 was maintained throughout. + # Zone NAME STDOFF RULES FORMAT [UNTIL] Zone America/Grand_Turk -4:44:32 - LMT 1890 -5:07:10 - KMT 1912 Feb # Kingston Mean Time -5:00 - EST 1979 - -5:00 US E%sT 2015 Nov Sun>=1 2:00 - -4:00 - AST 2018 Mar 11 3:00 + -5:00 US E%sT 2015 Mar 8 2:00 + -4:00 - AST 2018 Mar 11 3:00 -5:00 US E%sT # British Virgin Is -- 2.15.1