proposed tz changes (zdump.c, backward, and systemv)

Tue Nov 22 18:20:21 UTC 2005

"Olson, Arthur David \(NIH/NCI\)" <olsona at dc37a.nci.nih.gov> writes:

> The systemv stuff was included way back in 1986 when System V was
> still relevant; twenty years later it can presumably be dispensed with.

That sounds good to me.

By the way, I tried but failed to find documentation about exactly
which TZ settings Unix System V supported, and when this was
introduced (SVR1? SVR3? etc.).  If anybody has more concrete
information about this please let me know.  For now, the patch below
sticks with the same small set of seven backward-compatibility
settings that the current tz database supports.

> If we do end up with two copies of the US rules, we'll want to make sure
> that there's a comment with each copy indicating the need to keep it in
> sync with the other copy.

Elsewhere we have been using two copies (e.g., Russia in "europe"
versus RussiaAsia in "asia") so it is a little more consistent to
keep doing that, until we come up with a better way to attack the
issue.

Here's a revised patch along those lines.  It assumes that the
"systemv" file is removed.

--- backward	2005/08/29 15:54:31	2005.13
+++ backward	2005/11/22 18:05:09	2005.13.0.3
@@ -42,7 +42,6 @@ Link	America/Rio_Branco	Brazil/Acre
 Link	America/Noronha		Brazil/DeNoronha
 Link	America/Sao_Paulo	Brazil/East
 Link	America/Manaus		Brazil/West
-Link	America/Chicago		CST6CDT
 Link	America/Halifax		Canada/Atlantic
 Link	America/Winnipeg	Canada/Central
 Link	America/Regina		Canada/East-Saskatchewan
@@ -55,8 +54,6 @@ Link	America/Whitehorse	Canada/Yukon
 Link	America/Santiago	Chile/Continental
 Link	Pacific/Easter		Chile/EasterIsland
 Link	America/Havana		Cuba
-Link	America/Panama		EST
-Link	America/New_York	EST5EDT
 Link	Africa/Cairo		Egypt
 Link	Europe/Dublin		Eire
 Link	Europe/London		Europe/Belfast
@@ -67,7 +64,6 @@ Link	Etc/GMT			GMT+0
 Link	Etc/GMT			GMT-0
 Link	Etc/GMT			GMT0
 Link	Etc/GMT			Greenwich
-Link	Pacific/Honolulu	HST
 Link	Asia/Hong_Kong		Hongkong
 Link	Atlantic/Reykjavik	Iceland
 Link	Asia/Tehran		Iran
@@ -76,8 +72,6 @@ Link	America/Jamaica		Jamaica
 Link	Asia/Tokyo		Japan
 Link	Pacific/Kwajalein	Kwajalein
 Link	Africa/Tripoli		Libya
-Link	America/Phoenix		MST
-Link	America/Denver		MST7MDT
 Link	America/Tijuana		Mexico/BajaNorte
 Link	America/Mazatlan	Mexico/BajaSur
 Link	America/Mexico_City	Mexico/General
@@ -85,7 +79,6 @@ Link	Pacific/Auckland	NZ
 Link	Pacific/Chatham		NZ-CHAT
 Link	America/Denver		Navajo
 Link	Asia/Shanghai		PRC
-Link	America/Los_Angeles	PST8PDT
 Link	Pacific/Pago_Pago	Pacific/Samoa
 Link	Pacific/Truk		Pacific/Yap
 Link	Europe/Warsaw		Poland
@@ -111,3 +104,35 @@ Link	Etc/UTC			UTC
 Link	Etc/UTC			Universal
 Link	Europe/Moscow		W-SU
 Link	Etc/UTC			Zulu
+
+
+# A copy of the US rules from the "northamerica" file.
+# The copy is so that "backward" can be compiled independently.
+# Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
+Rule	US-back	1918	1919	-	Mar	lastSun	2:00	1:00	D
+Rule	US-back	1918	1919	-	Oct	lastSun	2:00	0	S
+Rule	US-back	1942	only	-	Feb	9	2:00	1:00	W # War
+Rule	US-back	1945	only	-	Aug	14	23:00u	1:00	P # Peace
+Rule	US-back	1945	only	-	Sep	30	2:00	0	S
+Rule	US-back	1967	2006	-	Oct	lastSun	2:00	0	S
+Rule	US-back	1967	1973	-	Apr	lastSun	2:00	1:00	D
+Rule	US-back	1974	only	-	Jan	6	2:00	1:00	D
+Rule	US-back	1975	only	-	Feb	23	2:00	1:00	D
+Rule	US-back	1976	1986	-	Apr	lastSun	2:00	1:00	D
+Rule	US-back	1987	2006	-	Apr	Sun>=1	2:00	1:00	D
+Rule	US-back	2007	max	-	Mar	Sun>=8	2:00	1:00	D
+Rule	US-back	2007	max	-	Nov	Sun>=1	2:00	0	S
+# Keep the above rules in sync with the "US" rules in the "northamerica" file.
+
+# The following zones are for backward compatibility with TZ settings
+# supported by 1980s-era Unix System V.
+
+# Zone	NAME		GMTOFF	RULES	FORMAT
+Zone	EST	 -5:00	-	EST
+Zone	MST	 -7:00	-	MST
+Zone	HST	-10:00	-	HST
+
+Zone	EST5EDT	 -5:00	US-back	E%sT
+Zone	CST6CDT	 -6:00	US-back	C%sT
+Zone	MST7MDT	 -7:00	US-back	M%sT
+Zone	PST8PDT	 -8:00	US-back	P%sT
--- northamerica	2005/11/18 06:54:05	2005.14.0.1
+++ northamerica	2005/11/22 18:04:38	2005.14.0.2
@@ -130,6 +130,7 @@ Rule	US	1976	1986	-	Apr	lastSun	2:00	1:0
 Rule	US	1987	2006	-	Apr	Sun>=1	2:00	1:00	D
 Rule	US	2007	max	-	Mar	Sun>=8	2:00	1:00	D
 Rule	US	2007	max	-	Nov	Sun>=1	2:00	0	S
+# Keep the above rules in sync with the "US-back" rules in the "backward" file.
 
 # From Bob Devine (1988-01-28):
 # ...Alaska (and Hawaii) had the timezone names changed in 1967.
--- Makefile	2005/07/14 18:13:37	2005.10
+++ Makefile	2005/11/22 18:07:53	2005.10.0.2
@@ -261,11 +261,10 @@ DOCS=		README Theory $(MANS) date.1 Make
 PRIMARY_YDATA=	africa antarctica asia australasia \
 		europe northamerica southamerica
 YDATA=		$(PRIMARY_YDATA) pacificnew etcetera factory backward
-NDATA=		systemv
 SDATA=		solar87 solar88 solar89
-TDATA=		$(YDATA) $(NDATA) $(SDATA)
+TDATA=		$(YDATA) $(SDATA)
 TABDATA=	iso3166.tab zone.tab
-DATA=		$(YDATA) $(NDATA) $(SDATA) $(TABDATA) leapseconds yearistype.sh
+DATA=		$(TDATA) $(TABDATA) leapseconds yearistype.sh
 WEB_PAGES=	tz-art.htm tz-link.htm
 MISC=		usno1988 usno1989 usno1989a usno1995 usno1997 usno1998 \
 			itca.jpg $(WEB_PAGES) checktab.awk workman.sh

