Dear Sirs,

I have been working with the 2000h version of the time zone and daylight
savings time data at 
ftp://elsie.nci.nih.gov/pub/tzdata2000h.tar.gz , and
ftp://elsie.nci.nih.gov/pub/tzcode2000h.tar.gz .

I have found some unusual results in the rules files for time zones
in Brazil.  I have given a high level statement of the unusual, and
then detailed output from the zdump command later.
Do you get similiar results from the zdump command?
Have I made a mistake in understanding the zdump results?
Is there any way that I can help clear this up?

***  Local Name BRT 3 BRST in Brazil
The time zone America/Recife has a seven day long Daylight Savings Time (DST)
in October 2000, and no DST in 1991-1998, 2001, and beyond.

The time zone America/Maceio has a fourteen day long Daylight Savings Time (DST)
in October 2000, and no DST in 1991-1994, 1997, 1998, 2001, and beyond.

The time zone America/Fortaleza has a fourteen day long Daylight Savings Time (DST)
in October 2000, and no DST in 1991-1998, 2001, and beyond.

The time zones America/Araguaina and America/Sao_Paulo have the same local names 
as the three time zones above.  They are all in Brazil.  These time zones have
reasonable length DST in 2000, and 2001.  These look OK.

***  Local Name AMT 4 AMST in Brazil
The time zone America/Boa_Vista has a seven day long Daylight Savings Time (DST)
in October 2000, and no DST in 1988-1998, 2001, and beyond.

The time zone America/Cuiaba has the same local name.  They are both in Brazil.
This time zone has reasonable length DST in 2000, and 2001.  This looks OK.


***  Details

***
The time zone America/Recife has a seven day long Daylight Savings Time (DST)
in October 2000, and no DST in 1991-1998, 2001, and beyond.

The following is an exerpt from "zdump -v America/Recife".
America/Recife  Sun Feb 11 01:59:59 1990 UTC = Sat Feb 10 23:59:59 1990 BRST isdst=1
America/Recife  Sun Feb 11 02:00:00 1990 UTC = Sat Feb 10 23:00:00 1990 BRT isdst=0
America/Recife  Sun Oct  3 02:59:59 1999 UTC = Sat Oct  2 23:59:59 1999 BRT isdst=0
America/Recife  Sun Oct  3 03:00:00 1999 UTC = Sun Oct  3 01:00:00 1999 BRST isdst=1
America/Recife  Sun Feb 27 01:59:59 2000 UTC = Sat Feb 26 23:59:59 2000 BRST isdst=1
America/Recife  Sun Feb 27 02:00:00 2000 UTC = Sat Feb 26 23:00:00 2000 BRT isdst=0
America/Recife  Sun Oct  8 02:59:59 2000 UTC = Sat Oct  7 23:59:59 2000 BRT isdst=0
America/Recife  Sun Oct  8 03:00:00 2000 UTC = Sun Oct  8 01:00:00 2000 BRST isdst=1
America/Recife  Sun Oct 15 01:59:59 2000 UTC = Sat Oct 14 23:59:59 2000 BRST isdst=1
America/Recife  Sun Oct 15 02:00:00 2000 UTC = Sat Oct 14 23:00:00 2000 BRT isdst=0
America/Recife  Mon Jan 18 03:14:07 2038 UTC = Mon Jan 18 00:14:07 2038 BRT isdst=0
America/Recife  Tue Jan 19 03:14:07 2038 UTC = Tue Jan 19 00:14:07 2038 BRT isdst=0

***
The time zone America/Maceio has a fourteen day long Daylight Savings Time (DST)
in October 2000, and no DST in 1991-1994, 1997, 1998, 2001, and beyond.

The following is an exerpt from "zdump -v America/Maceio".
America/Maceio  Sun Feb 11 01:59:59 1990 UTC = Sat Feb 10 23:59:59 1990 BRST isdst=1
America/Maceio  Sun Feb 11 02:00:00 1990 UTC = Sat Feb 10 23:00:00 1990 BRT isdst=0
America/Maceio  Sun Oct 15 02:59:59 1995 UTC = Sat Oct 14 23:59:59 1995 BRT isdst=0
America/Maceio  Sun Oct 15 03:00:00 1995 UTC = Sun Oct 15 01:00:00 1995 BRST isdst=1
America/Maceio  Sun Feb 11 01:59:59 1996 UTC = Sat Feb 10 23:59:59 1996 BRST isdst=1
America/Maceio  Sun Feb 11 02:00:00 1996 UTC = Sat Feb 10 23:00:00 1996 BRT isdst=0
America/Maceio  Sun Oct  3 02:59:59 1999 UTC = Sat Oct  2 23:59:59 1999 BRT isdst=0
America/Maceio  Sun Oct  3 03:00:00 1999 UTC = Sun Oct  3 01:00:00 1999 BRST isdst=1
America/Maceio  Sun Feb 27 01:59:59 2000 UTC = Sat Feb 26 23:59:59 2000 BRST isdst=1
America/Maceio  Sun Feb 27 02:00:00 2000 UTC = Sat Feb 26 23:00:00 2000 BRT isdst=0
America/Maceio  Sun Oct  8 02:59:59 2000 UTC = Sat Oct  7 23:59:59 2000 BRT isdst=0
America/Maceio  Sun Oct  8 03:00:00 2000 UTC = Sun Oct  8 01:00:00 2000 BRST isdst=1
America/Maceio  Sun Oct 22 01:59:59 2000 UTC = Sat Oct 21 23:59:59 2000 BRST isdst=1
America/Maceio  Sun Oct 22 02:00:00 2000 UTC = Sat Oct 21 23:00:00 2000 BRT isdst=0
America/Maceio  Mon Jan 18 03:14:07 2038 UTC = Mon Jan 18 00:14:07 2038 BRT isdst=0
America/Maceio  Tue Jan 19 03:14:07 2038 UTC = Tue Jan 19 00:14:07 2038 BRT isdst=0

***
The time zone America/Fortaleza has a fourteen day long Daylight Savings Time (DST)
in October 2000, and no DST in 1991-1998, 2001, and beyond.

The following is an exerpt from "zdump -v America/Fortaleza".
America/Fortaleza  Sun Feb 11 01:59:59 1990 UTC = Sat Feb 10 23:59:59 1990 BRST isdst=1
America/Fortaleza  Sun Feb 11 02:00:00 1990 UTC = Sat Feb 10 23:00:00 1990 BRT isdst=0
America/Fortaleza  Sun Oct  3 02:59:59 1999 UTC = Sat Oct  2 23:59:59 1999 BRT isdst=0
America/Fortaleza  Sun Oct  3 03:00:00 1999 UTC = Sun Oct  3 01:00:00 1999 BRST isdst=1
America/Fortaleza  Sun Feb 27 01:59:59 2000 UTC = Sat Feb 26 23:59:59 2000 BRST isdst=1
America/Fortaleza  Sun Feb 27 02:00:00 2000 UTC = Sat Feb 26 23:00:00 2000 BRT isdst=0
America/Fortaleza  Sun Oct  8 02:59:59 2000 UTC = Sat Oct  7 23:59:59 2000 BRT isdst=0
America/Fortaleza  Sun Oct  8 03:00:00 2000 UTC = Sun Oct  8 01:00:00 2000 BRST isdst=1
America/Fortaleza  Sun Oct 22 01:59:59 2000 UTC = Sat Oct 21 23:59:59 2000 BRST isdst=1
America/Fortaleza  Sun Oct 22 02:00:00 2000 UTC = Sat Oct 21 23:00:00 2000 BRT isdst=0
America/Fortaleza  Mon Jan 18 03:14:07 2038 UTC = Mon Jan 18 00:14:07 2038 BRT isdst=0
America/Fortaleza  Tue Jan 19 03:14:07 2038 UTC = Tue Jan 19 00:14:07 2038 BRT isdst=0

***
The time zone America/Boa_Vista has a seven day long Daylight Savings Time (DST)
in October 2000, and no DST in 1988-1998, 2001, and beyond.

The following is an exerpt from "zdump -v America/Boa_Vista".
America/Boa_Vista  Sun Feb  7 02:59:59 1988 UTC = Sat Feb  6 23:59:59 1988 AMST isdst=1
America/Boa_Vista  Sun Feb  7 03:00:00 1988 UTC = Sat Feb  6 23:00:00 1988 AMT isdst=0
America/Boa_Vista  Sun Oct  3 03:59:59 1999 UTC = Sat Oct  2 23:59:59 1999 AMT isdst=0
America/Boa_Vista  Sun Oct  3 04:00:00 1999 UTC = Sun Oct  3 01:00:00 1999 AMST isdst=1
America/Boa_Vista  Sun Feb 27 02:59:59 2000 UTC = Sat Feb 26 23:59:59 2000 AMST isdst=1
America/Boa_Vista  Sun Feb 27 03:00:00 2000 UTC = Sat Feb 26 23:00:00 2000 AMT isdst=0
America/Boa_Vista  Sun Oct  8 03:59:59 2000 UTC = Sat Oct  7 23:59:59 2000 AMT isdst=0
America/Boa_Vista  Sun Oct  8 04:00:00 2000 UTC = Sun Oct  8 01:00:00 2000 AMST isdst=1
America/Boa_Vista  Sun Oct 15 02:59:59 2000 UTC = Sat Oct 14 23:59:59 2000 AMST isdst=1
America/Boa_Vista  Sun Oct 15 03:00:00 2000 UTC = Sat Oct 14 23:00:00 2000 AMT isdst=0
America/Boa_Vista  Mon Jan 18 03:14:07 2038 UTC = Sun Jan 17 23:14:07 2038 AMT isdst=0
America/Boa_Vista  Tue Jan 19 03:14:07 2038 UTC = Mon Jan 18 23:14:07 2038 AMT isdst=0