>From 398e7139b6b4d2abfb8f776c3f1bad4d11f50759 Mon Sep 17 00:00:00 2001
From: Paul Eggert +
' 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'.