Time Zones changes in Argentina

Paul Eggert eggert at twinsun.com
Wed Jan 23 06:10:48 UTC 2002


Thanks for your letter.  The tz files acquired some incorrect data
about Argentine time from the 3rd edition of Shanks's International Atlas.
I now see that the 5th edition corrects this; I'd missed this earlier.

>From what I understand, here are the changes that I think need making
with respect to Argentine time.

* No DST was observed from mid-1974 through mid-1988.

* 1966/1967 DST ended on 1967-04-02, not 1967-04-01.

* Argentine standard time was introduced 1894-10-31, not 1894-11-01.

* Argentine standard time from 1894-10-31 through 1920-04-30 was
  -4:16:48.25, not -4:16:44.

* Rosario and Cordoba have the same time zone history since 1970,
  so we should mark the America/Rosario Zone as obsolescent.

* Many of the transition dates in 1991 and 1992 are incorrect.

If you see any problems with these changes, please let me know.

It appears that there was widespread disagreement about the clocks in
Argentina in 1991 and 1992.  Shanks also indicates that we may need up
to six more regions in Argentina, as he makes the following additional
claims:

  - Formosa switched to -3:00 on 1991-01-07.
  - La Rioja and San Juan switched to -4:00 on 1991-03-01
    and then to 03:00 on 1991-05-07.
  - Misiones switched to -3:00 on 1990-12-29.
  - Chaco switched to -3:00 on 1991-01-04.
  - San Luis switched to -4:00 on 1990-03-14, then to -3:00 on 1990-10-15,
    then to -4:00 on 1991-03-01, then to -3:00 on 1991-06-01.
  - Santiago del Estero switched to -4:00 on 1991-04-01,
    then to -3:00 on 1991-04-26.

However, his claims are a bit odd, and his data about this confusing
area seem to peter out around 1992 even though the book was published
in 1999.  I think I'll defer adding Zones for each of these regions
until we get more info.


If you're interested, here is the draft of some revised tables for
Argentina.  I'll included these in my next proposed patch.


# Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
Rule	Arg	1930	only	-	Dec	 1	0:00	1:00	S
Rule	Arg	1931	only	-	Apr	 1	0:00	0	-
Rule	Arg	1931	only	-	Oct	15	0:00	1:00	S
Rule	Arg	1932	1940	-	Mar	 1	0:00	0	-
Rule	Arg	1932	1939	-	Nov	 1	0:00	1:00	S
Rule	Arg	1940	only	-	Jul	 1	0:00	1:00	S
Rule	Arg	1941	only	-	Jun	15	0:00	0	-
Rule	Arg	1941	only	-	Oct	15	0:00	1:00	S
Rule	Arg	1943	only	-	Aug	 1	0:00	0	-
Rule	Arg	1943	only	-	Oct	15	0:00	1:00	S
Rule	Arg	1946	only	-	Mar	 1	0:00	0	-
Rule	Arg	1946	only	-	Oct	 1	0:00	1:00	S
Rule	Arg	1963	only	-	Oct	 1	0:00	0	-
Rule	Arg	1963	only	-	Dec	15	0:00	1:00	S
Rule	Arg	1964	1966	-	Mar	 1	0:00	0	-
Rule	Arg	1964	1966	-	Oct	15	0:00	1:00	S
Rule	Arg	1967	only	-	Apr	 2	0:00	0	-
Rule	Arg	1967	1968	-	Oct	Sun>=1	0:00	1:00	S
Rule	Arg	1968	1969	-	Apr	Sun>=1	0:00	0	-
Rule	Arg	1974	only	-	Jan	23	0:00	1:00	S
Rule	Arg	1974	only	-	May	 1	0:00	0	-
Rule	Arg	1988	only	-	Dec	 1	0:00	1:00	S
Rule	Arg	1989	1993	-	Mar	Sun>=1	0:00	0	-
Rule	Arg	1989	1992	-	Oct	Sun>=15	0:00	1:00	S
Rule	Arg	1999	only	-	Oct	Sun>=1	0:00	1:00	S
Rule	Arg	2000	only	-	Mar	Sun>=1	0:00	0	-


# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
#
# Buenos Aires (BA), Capital Federal (CF), Santa Cruz (SC),
# Tierra del Fuego, Antartida e Islas del Atlantico Sur (TF)
Zone America/Buenos_Aires -3:53:48 -	LMT	1894 Oct 31
			-4:16:48 -	CMT	1920 May # Cordoba Mean Time
			-4:00	-	ART	1930 Dec
			-4:00	Arg	AR%sT	1969 Oct  5
			-3:00	Arg	AR%sT	1999 Oct  3
			-4:00	Arg	AR%sT	2000 Mar  3
			-3:00	-	ART
#
# Santa Fe (SF), Entre Rios (ER), Corrientes (CN), Misiones (MN), Chaco (CC),
# Formosa (FM), Salta (SA), Tucuman (TM), Santiago del Estero (SE),
# Cordoba (CB), La Rioja (LR), San Juan (SJ), San Luis (SL), La Pampa (LP),
# Neuquen (NQ), Rio Negro (RN), Chubut (CH)
Zone America/Cordoba	-4:16:48 -	LMT	1894 Oct 31
			-4:16:48 -	CMT	1920 May
			-4:00	-	ART	1930 Dec
			-4:00	Arg	AR%sT	1969 Oct  5
			-3:00	Arg	AR%sT	1991 Mar  3
			-4:00	-	WART	1991 Oct 20
			-3:00	Arg	AR%sT	1999 Oct  3
			-4:00	Arg	AR%sT	2000 Mar  3
			-3:00	-	ART
#
# Jujuy (JY)
Zone America/Jujuy	-4:21:12 -	LMT	1894 Oct 31
			-4:16:48 -	CMT	1920 May
			-4:00	-	ART	1930 Dec
			-4:00	Arg	AR%sT	1969 Oct  5
			-3:00	Arg	AR%sT	1990 Mar  4
			-4:00	-	WART	1990 Oct 28
			-4:00	1:00	WARST	1991 Mar 17
			-4:00	-	WART	1991 Oct  6
			-3:00	1:00	ARST	1992
			-3:00	Arg	AR%sT	1999 Oct  3
			-4:00	Arg	AR%sT	2000 Mar  3
			-3:00	-	ART
#
# Catamarca (CT)
Zone America/Catamarca	-4:23:08 -	LMT	1894 Oct 31
			-4:16:48 -	CMT	1920 May
			-4:00	-	ART	1930 Dec
			-4:00	Arg	AR%sT	1969 Oct  5
			-3:00	Arg	AR%sT	1991 Mar  3
			-4:00	-	WART	1991 Oct 20
			-3:00	Arg	AR%sT	1999 Oct  3
			-4:00	Arg	AR%sT	2000 Mar  3
			-3:00	-	ART
#
# Mendoza (MZ)
Zone America/Mendoza	-4:35:16 -	LMT	1894 Oct 31
			-4:16:48 -	CMT	1920 May
			-4:00	-	ART	1930 Dec
			-4:00	Arg	AR%sT	1969 Oct  5
			-3:00	Arg	AR%sT	1990 Mar  4
			-4:00	-	WART	1990 Oct 15
			-4:00	1:00	WARST	1991 Mar  1
			-4:00	-	WART	1991 Oct 15
			-4:00	1:00	WARST	1992 Mar  1
			-4:00	-	WART	1992 Oct 18
			-3:00	Arg	AR%sT	1999 Oct  3
			-4:00	Arg	AR%sT	2000 Mar  3
			-3:00	-	ART



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