[tz] Fiji daylight savings

Paul Eggert eggert at cs.ucla.edu
Mon Sep 9 19:51:03 UTC 2013


Thanks for the heads-up.  It looks like timeanddate.com guessed right
for October 2013 and wrong for January 2014 whereas we did the
reverse.  Here's a proposed patch, which I've pushed to the
experimental repository on github.  We will need a new stable
release soon, to accommodate this change to near-future time stamps.

The new Fiji rules provide an independent test of the proposed
version-3-format changes for extensions to POSIX TZ strings.
It worked.  This patch updates the newtzset.3 Fiji example
to match the new rules.

Does anyone have info on what the general rule is for Fiji?
If so, we should be able to improve our predictions in the future.

>From 8ee0fbebc6a1723eb4d3666e359afc7dcef3e413 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert at cs.ucla.edu>
Date: Mon, 9 Sep 2013 12:39:51 -0700
Subject: [PATCH] Reflect Fiji DST change planned for October.

Reported by David Wheeler in
<http://mm.icann.org/pipermail/tz/2013-September/020083.html>.
* australasia (Fiji): Tweak spring-forward transitions to match
timeanddate.com's predictions.
* newtzset.3: Adjust Fiji example to match updated predictions.
Reword examples so that the English descriptions are more
consistent and are roughly in the same order as the TZ string
contents.
---
 australasia | 15 ++++++++++++---
 newtzset.3  | 35 ++++++++++++++++++-----------------
 2 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/australasia b/australasia
index 3e1bfc6..c822b08 100644
--- a/australasia
+++ b/australasia
@@ -352,16 +352,25 @@ Zone    Indian/Cocos    6:27:40    -    LMT    1900
 # today confirmed that Fiji will start daylight savings at 2 am on
Sunday 21st
 # October 2012 and end at 3 am on Sunday 20th January 2013.
 #
http://www.fiji.gov.fj/index.php?option=com_content&view=article&id=6702&catid=71&Itemid=155
+
+# From the Fijian Government Media Center (2013-08-30) via David Wheeler:
+# Fiji will start daylight savings on Sunday 27th October, 2013 and end
at 3am
+# on Sunday 19th January, 2014....  move clocks forward by one hour
from 2am
+#
http://www.fiji.gov.fj/Media-Center/Press-Releases/DAYLIGHT-SAVING-STARTS-ON-SUNDAY,-27th-OCTOBER-201.aspx
 #
-# From Paul Eggert (2012-08-31):
-# For now, guess a pattern of the penultimate Sundays in October and
January.
+# From Paul Eggert (2013-09-09):
+# For now, guess that Fiji springs forward the Sunday before the fourth
+# Monday in October.  This matches both recent practice and
+# timeanddate.com's current spring-forward prediction.
+# For the January 2014 transition we guessed right while timeanddate.com
+# guessed wrong, so leave the fall-back prediction alone.
 
 # Rule    NAME    FROM    TO    TYPE    IN    ON    AT    SAVE    LETTER/S
 Rule    Fiji    1998    1999    -    Nov    Sun>=1    2:00    1:00    S
 Rule    Fiji    1999    2000    -    Feb    lastSun    3:00    0    -
 Rule    Fiji    2009    only    -    Nov    29    2:00    1:00    S
 Rule    Fiji    2010    only    -    Mar    lastSun    3:00    0    -
-Rule    Fiji    2010    max    -    Oct    Sun>=18    2:00    1:00    S
+Rule    Fiji    2010    max    -    Oct    Sun>=21    2:00    1:00    S
 Rule    Fiji    2011    only    -    Mar    Sun>=1    3:00    0    -
 Rule    Fiji    2012    max    -    Jan    Sun>=18    3:00    0    -
 # Zone    NAME        GMTOFF    RULES    FORMAT    [UNTIL]
diff --git a/newtzset.3 b/newtzset.3
index 618c92d..3462f4f 100644
--- a/newtzset.3
+++ b/newtzset.3
@@ -203,34 +203,35 @@ extensions to POSIX.
 stands for US eastern
 time (EST), 5 hours behind UTC, without daylight saving.
 .TP
-.B FJT\(mi12FJST,M10.3.4/74,M1.3.4/75
+.B FJT\(mi12FJST,M10.3.1/146,M1.3.4/75
 stands for Fiji Time (FJT) and Fiji Summer Time (FJST), 12 hours ahead
-of UTC, where clocks spring forward at 74:00 on the third Thursday in
-October (i.e., 02:00 on the first Sunday on or after October 18), and
-fall back at 75:00 on the third Thursday in January (i.e., 03:00 on
-the first Sunday on or after January 18).
+of UTC, springing forward on October's third Monday at
+146:00 (i.e., 02:00 on the first Sunday on or after October 21), and
+falling back on January's third Thursday at 75:00 (i.e., 03:00 on the
+first Sunday on or after January 18).
 .TP
 .B IST\(mi2IDT,M3.4.4/26,M10.5.0
-stands for Israel standard time (IST) and Israel daylight time (IDT),
-2 hours ahead of UTC, where clocks spring forward at 26:00 on the
-fourth Thursday in March (i.e., 02:00 on the first Friday on or after
-March 23), and fall back at 02:00 on the last Sunday in October.
+stands for Israel Standard Time (IST) and Israel Daylight Time (IDT),
+2 hours ahead of UTC, springing forward on March's fourth
+Tuesday at 26:00 (i.e., 02:00 on the first Friday on or after March
+23), and falling back on October's last Sunday at 02:00.
 .TP
 .B WART4WARST,J1/0,J365/25
 stands for Western Argentina Summer Time (WARST), 3 hours behind UTC.
-There is a dummy transition to standard time on December 31 at 25:00
-daylight saving time (i.e., 24:00 standard time, equivalent to January
-1 at 00:00 standard time), and a simultaneous transition to daylight
-saving time on January 1 at 00:00 standard time, so daylight saving
-time is in effect all year and the initial
+There is a dummy fall-back transition on December 31 at 25:00 daylight
+saving time (i.e., 24:00 standard time, equivalent to January 1 at
+00:00 standard time), and a simultaneous spring-forward transition on
+January 1 at 00:00 standard time, so daylight saving time is in effect
+all year and the initial
 .B WART
 is a placeholder.
 .TP
 .B WGT3WGST,M3.5.0/\(mi2,M10.5.0/\(mi1
-stands for Western Greenland Time (WGT) and Western Greenland Summer
+stands for Western Greenland time (WGT) and Western Greenland Summer
 Time (WGST), 3 hours behind UTC, where clocks follow the EU rules of
-springing forward the last Sunday in March at \(mi02:00 (i.e., 01:00 UTC)
-and falling back the last Sunday in October at \(mi01:00 (i.e., 01:00 UTC).
+springing forward on March's last Sunday at 01:00 UTC (\(mi02:00 local
+time) and falling back on October's last Sunday at 01:00 UTC
+(\(mi01:00 local time).
 .PP
 If no
 .I rule
-- 
1.8.3.1




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