>From 398e7139b6b4d2abfb8f776c3f1bad4d11f50759 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Mon, 4 Dec 2017 09:26:52 -0800 Subject: [PROPOSED 1/3] Mention Irish Summer Time in theory.html * theory.html (Time zone abbreviations): Also mention IST for Irish Summer Time (thanks to Derick Rethans). Fix regular expression to match rest of commentary. --- theory.html | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/theory.html b/theory.html index c432cc9..cc2d3d2 100644 --- a/theory.html +++ b/theory.html @@ -297,7 +297,7 @@ in decreasing order of importance: '+' and '-' are safe in all locales. In other words, in the C locale the POSIX extended regular - expression [-+[:alnum:]]{3,} should match + expression [-+[:alnum:]]{3,6} should match the abbreviation. This guarantees that all abbreviations could have been specified by a POSIX TZ string. @@ -322,7 +322,7 @@ CET/CEST/CEMT Central European, ChST Chamorro, CST/CDT/CWT/CPT/CDDT Central [North America], CST/CDT China, -GMT/BST/BDST Greenwich, +GMT/BST/IST/BDST Greenwich, EAT East Africa, EST/EDT/EWT/EPT/EDDT Eastern [North America], EET/EEST Eastern European, @@ -387,10 +387,11 @@ TMT Tallinn, Tehran; WMT Warsaw.

A few abbreviations also follow the pattern that -GMT/BST/BDST established for time in the UK. They are: +GMT/BST/IST/BDST established for time in the UK. They are: CMT/BST for Calamarca Mean Time and Bolivian Summer Time -1890–1932, MMT/MST/MDST for Moscow 1880–1919, and RMT/LST +1890–1932, DMT/IST for Dublin Mean Time and Irish Summer Time +1880–1916, MMT/MST/MDST for Moscow 1880–1919, and RMT/LST for Riga Mean Time and Latvian Summer time 1880–1926. An extra-special case is SET for Swedish Time (svensk normaltid) 1879–1899, 3° west of the Stockholm @@ -431,10 +432,10 @@ Observatory.

Application writers should note that these abbreviations are ambiguous -in practice: e.g. 'CST' has a different meaning in China than -it does in the United States. In new applications, it's often better -to use numeric UT offsets like '-0600' instead of time zone -abbreviations like 'CST'; this avoids the ambiguity. +in practice: e.g., 'CST' means one thing in China and something else +in North America, and 'IST' can refer to time in India, Ireland or +Israel. To avoid ambiguity, use numeric UT offsets like +'-0600' instead of time zone abbreviations like 'CST'.

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