tzdata2001a from elsie.nci.nih.gov

1 files changed, 19 insertions, 7 deletions

diff --git a/share/zoneinfo/datfiles/etcetera b/share/zoneinfo/datfiles/etcetera
index b2bef804fb5..f87a76ea48a 100644
--- a/share/zoneinfo/datfiles/etcetera
+++ b/share/zoneinfo/datfiles/etcetera
@@ -1,6 +1,4 @@
-#	$OpenBSD: etcetera,v 1.6 2001/02/03 08:25:17 niklas Exp $
-
-# @(#)etcetera	7.10
+# @(#)etcetera	7.11
 
 # These entries are mostly present for historical reasons, so that
 # people in areas not otherwise covered by the tz files could "zic -l"
@@ -26,10 +24,24 @@ Link	Etc/GMT				Etc/GMT-0
 Link	Etc/GMT				Etc/GMT+0
 Link	Etc/GMT				Etc/GMT0
 
-# We use POSIX-style signedness in the names and output,
-# internal-style signedness in the specifications.
-# For example, TZ=Etc/GMT+4 corresponds to 4 hours _behind_ UTC;
-# it is equivalent to TZ=GMT+4, which is implemented directly as per POSIX.
+# We use POSIX-style signs in the Zone names and the output abbreviations,
+# even though this is the opposite of what many people expect.
+# POSIX has positive signs west of Greenwich, but many people expect
+# positive signs east of Greenwich.  For example, TZ='Etc/GMT+4' uses
+# the abbreviation "GMT+4" and corresponds to 4 hours behind UTC
+# (i.e. west of Greenwich) even though many people would expect it to
+# mean 4 hours ahead of UTC (i.e. east of Greenwich).
+#
+# In the draft 5 of POSIX 1003.1-200x, the angle bracket notation
+# (which is not yet supported by the tz code) allows for
+# TZ='<GMT-4>+4'; if you want time zone abbreviations conforming to
+# ISO 8601 you can use TZ='<-0400>+4'.  Thus the commonly-expected
+# offset is kept within the angle bracket (and is used for display)
+# while the POSIX sign is kept outside the angle bracket (and is used
+# for calculation).
+#
+# Do not use a TZ setting like TZ='GMT+4', which is four hours behind
+# GMT but uses the completely misleading abbreviation "GMT".
 
 # Earlier incarnations of this package were not POSIX-compliant,
 # and had lines such as