TZ changes for Brazil for 2003/2004

Oscar van Vlijmen ovv at
Mon Sep 22 18:57:23 UTC 2003

>> The information in
>> <>
>> is a RECOMMENDATION from the Ministry of Mines & Energy.
>> Very likely a presidential decree will follow some time later.
> Is it plausible that any presidential decree will differ from
> <>?
> I don't know Brazilian politics, unfortunately; nor can I read
> Portuguese.  But I don't see anything in that press release that
> indicates that it's merely a recommendation, and might change.

The press release of the Minister of Mines & Energy refers to the
Informative Note, which is according to its text a recommendation.
Makes sense. The minister does a recommendation, the president converts it
into a decree. The president could depart from the recommendation however.

>> See also decree no. 2784 from 1913 about the definition of the "legal hour".
> Sorry, I don't have access to that document.

I've read it. In fact it defines the 4 timezones in Brazil as so and so many
hours from GMT (now UT).

Paulo Alexandre Pinto Pires gives in his email dated Sept. 22 a coarse

An interesting detail in the original is that the exact division of the
timezone borders in Pará and Amazonas are given.
My interpretation, brought up to date:

For Pará the division is the river Xingu. In the north a very small part
from the river Javary (now Jari I guess, the border with Amapá) to the
Amazone, then to the Xingu.
For Amazonas the division is the great circle line from Tabatinga to Porto
These definitions are more precise than just east/west as the tz-database

The last "summertime" decree no. 4399 said:
"A partir de zero hora do dia 3 de novembro de 2002, até zero hora do dia 16
de fevereiro de 2003...".
So: [summertime is instituted] from [Sunday] 0 h November 3 2002 until
[Sunday] 0 h February 16 2003.
Exactly what is meant by "zero hour" is not defined.

If you can't see the point in this, please be aware of the fact that someone
who lives in Brazil can probably not imagine why someone not living in
Brazil doesn't know when exactly the clocks are changed.

Luckily I found a confirmation of the exact times of change at the National
"Início do Horário de Verão
Nesses Estados [described above, not copied here. OvV], quando os relógios
estiverem marcando 00:00 (zero hora ) do dia 03 de novembro de 2002, deverão
ser adiantados de 1 hora ( ou seja, deverão ser alterados para 01:00 (uma
hora) da manhã do dia 03 de novembro de 2002)."
"Término do Horário de Verão
Nesses Estados, quando os relógios estiverem marcando 00:00 (zero hora ) do
dia 16 de fevereiro de 2003, deverão ser atrasados de 1 hora ( ou seja,
deverão ser alterados para 23:00 do dia 15 de fevereiro de 2003)."

So: summertime starts when the clock reads 00:00 h [wall clock time], to be
advanced to 01:00.
And summertime ends when the clock reads 00:00 h Sunday [wall clock time],
to be set back to 23:00 h Saturday.

Strange to me, living in a country where the clock is set back on Sunday
from 03:00 to 02:00. I am not accustomed to a practice where one goes back
to Saturday as soon as it gets Sunday! Hence my suspicion, but now we have

Oscar van Vlijmen
No need to Cc your replies to my email address; I get them from the

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