proposed patch for Mexico

[Paul Eggert]

I asked on the net about Mexico's DST rule change this year; the most
authoritative-sounding response I got was from Kevin Pitts, so I've
included his version in the patch proposed below.  Further corrections
may be needed, since there seems to be some confusion about the
changes; e.g. in http://mexico-travel.com/mex_eng.html, Mexico's
Ministry of Tourism claims that Mexico switched to US style DST rules
way back in spring 1994.

===================================================================
RCS file: RCS/northamerica,v
retrieving revision 1995.13
retrieving revision 1995.13.1.1
diff -c -r1995.13 -r1995.13.1.1
*** northamerica	1995/12/21 17:18:31	1995.13
--- northamerica	1996/02/10 04:40:26	1995.13.1.1
***************
*** 852,857 ****
--- 852,866 ----
  # Shanks also says there are four zones, but disagrees about the fourth.
  # Instead of GMT-6 with DST, he says there's GMT-8 without DST.
  
+ # From Paul Eggert (1996-02-07):
+ # Today in news:4f90v4$g6g at news.internet.com.mx, Kevin Pitts
+ # <bravo2 at internet.com.mx> wrote that Mexico will use Horario de Verano (DST)
+ # starting this year with the same rules as the US, and gave FIDE as a source.
+ # (FIDE is a private organization that promotes efficient electrical use.)
+ # On 1996-02-02 Mario Camou wrote that the transition times are Apr Sun>=1
+ # 0:00 and Nov 1 0:00 but also wrote ``The DST-out date looks a bit fishy''.
+ # Go with Pitts after 1996, and with Shanks before that.
+ 
  # From Shanks (1991):
  # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
  Rule	Mexico	1922	only	-	Jan	1	0:00	0	S
***************
*** 863,868 ****
--- 872,880 ----
  Rule	Mexico	1944	only	-	May	1	0:00	0	S
  Rule	Mexico	1950	only	-	Feb	12	0:00	1:00	D
  Rule	Mexico	1950	only	-	Jul	30	0:00	0	S
+ Rule	Mexico	1996	max	-	Apr	Sun>=1	2:00	1:00	D
+ Rule	Mexico	1996	max	-	Oct	lastSun	2:00	0	S
+ #
  Rule	BajaN	1950	1966	-	Apr	lastSun	2:00	1:00	D
  Rule	BajaN	1950	1961	-	Sep	lastSun	2:00	0	S
  Rule	BajaN	1961	1966	-	Oct	lastSun	2:00	0	S
***************
*** 883,902 ****
  			-6:00	-	CST	1942 Apr
  			-7:00	-	MST	1949 Jan 14
  			-8:00	-	PST	1970
! 			-7:00	-	MST
  Zone America/Tijuana	-7:48:04 -	LMT	1922 Jan  1  0:11:56
  			-8:00	-	PST	1927 Jun 10 23:00
  			-7:00	-	MST	1930 Nov 16
  			-8:00	-	PST	1942 Apr
  			-7:00	-	MST	1949 Jan 14
  			-8:00	BajaN	P%sT	1967 Apr lastSun 2:00
! 			-8:00	US	P%sT
  Zone America/Ensenada	-7:46:28 -	LMT	1922 Jan  1  0:13:32
  			-8:00	-	PST	1927 Jun 10 23:00
  			-7:00	-	MST	1930 Nov 16
  			-8:00	-	PST	1942 Apr
  			-7:00	-	MST	1949 Jan 14
! 			-8:00	-	PST
  #
  # Revillagigedo Is
  # no information
--- 895,916 ----
  			-6:00	-	CST	1942 Apr
  			-7:00	-	MST	1949 Jan 14
  			-8:00	-	PST	1970
! 			-7:00	Mexico	M%sT
  Zone America/Tijuana	-7:48:04 -	LMT	1922 Jan  1  0:11:56
  			-8:00	-	PST	1927 Jun 10 23:00
  			-7:00	-	MST	1930 Nov 16
  			-8:00	-	PST	1942 Apr
  			-7:00	-	MST	1949 Jan 14
  			-8:00	BajaN	P%sT	1967 Apr lastSun 2:00
! 			-8:00	US	P%sT	1996
! 			-8:00	Mexico	P%sT
  Zone America/Ensenada	-7:46:28 -	LMT	1922 Jan  1  0:13:32
  			-8:00	-	PST	1927 Jun 10 23:00
  			-7:00	-	MST	1930 Nov 16
  			-8:00	-	PST	1942 Apr
  			-7:00	-	MST	1949 Jan 14
! 			-8:00	-	PST	1996
! 			-8:00	Mexico	P%sT
  #
  # Revillagigedo Is
  # no information