Mexico DST news

Jesper Norgaard Welen jnorgard at
Tue Jan 23 05:30:29 UTC 2007

True, I forgot about the 1970 cutoff. Also the decree from March 23, 1989
was immediately revoked March 30, 1989 so it never came into effect. Perhaps
we don't need any new timezones. But there are changes anyway in the dates
and timezone rules as far as I can see. I will try and elaborate a
suggestion of changes to the tz database. 

I will elaborate it respecting changes on decree dates, but respecting
existing changes between decree dates, especially in the gap between 1948
and 1981. These decrees no doubt were issued, and followed. But we have no
guarantee that no more decrees exist, hence I want to respect the tz
database in between decree dates.

Also, if the tz database has one date, and the decree another date close-by,
I think we should go with the existing tz date because there is no guarantee
that the decree came into effect the date it says, in fact the date given is
the date the decree was published in the official "newspaper".

- Jesper Nørgaard Welen

-----Original Message-----
From: Paul Eggert [mailto:eggert at] 
Sent: Lunes, 22 de Enero de 2007 0:36
To: tz at
Subject: Re: Mexico DST news

Jesper Norgaard Welen <jnorgard at> writes:

> ulo5.htm

Yes, that's section 5 of the history of Mexican local time
that <> points to.

> If everything is taken literally, there are at
> least a need to introduce new timezones for the states Campeche, 
> Tamaulipas,
> Tabasco+CHS, Baja California Sur, Durango, Veracruz+Oaxaca, and 
> Tabasco+Coahuila.

Do these states have time zone histories that differ since 1970?  If so, we
would need new entries for them.  (I don't read Spanish well, alas).

> Before I go too far with deciphering this, I would like to hear the 
> general opinion about if this is an authoritative source or not - 
> after all the Congress only recently got authority over timezone 
> issues in Mexico (formally), and this list might have some goofed up 
> details from extracting from old documents by "new" people.

That could be, yes.  But I'm not really qualified to judge this,

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