system_cmds-279.tar.gz

[apple/system_cmds.git] / zic.tproj / datfiles / etcetera

diff --git a/zic.tproj/datfiles/etcetera b/zic.tproj/datfiles/etcetera
index 8786abed63e8d3189258f00a9059fd999c3b37c6..f87a76ea48a7000b533ea80c27fd45e8c533094c 100644 (file)
--- a/zic.tproj/datfiles/etcetera
+++ b/zic.tproj/datfiles/etcetera
@@ -1,5 +1,4 @@
-#      $OpenBSD: etcetera,v 1.3 1997/01/14 04:36:51 millert Exp $
-# @(#)etcetera 7.6
+# @(#)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"
@@ -11,6 +10,12 @@ Zone Etc/GMT         0       -       GMT
 Zone   Etc/UTC         0       -       UTC
 Zone   Etc/UCT         0       -       UCT
 
+# The following link uses older naming conventions,
+# but it belongs here, not in the file `backward',
+# as functions like gmtime load the "GMT" file to handle leap seconds properly.
+# We want this to work even on installations that omit the other older names.
+Link   Etc/GMT                         GMT
+
 Link   Etc/UTC                         Etc/Universal
 Link   Etc/UTC                         Etc/Zulu
 
@@ -19,10 +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_ GMT;
-# 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