WRT my previous comment: "I've got a parallel discussion going within Microsoft about this zone, and will share the findings of our research. "

Our research concluded that there is no known location in the state of Baja California that observes Mexican DST rules.  All are on US DST rules.  The 20km boundary mentioned in the law applies in the other Mexican states, but not in Baja California due to the exclusions mentioned in the same law.

This agrees with ADO’s observations about San Quintin.

Also, the Wikipedia information about San Quintin becoming its own municipality is outdated.  The decision was overturned by the Mexican supreme court due to jurisdictional issues.  See:

http://www2.scjn.gob.mx/juridica/engroses/cerrados/Publico/13000980.009-2688.doc

Thanks,

Matt Johnson
Microsoft

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Date: Sun, 1 Nov 2015 20:32:17 -0500
From: arthurdavidolson@gmail.com
To: tz@iana.org
Subject: Re: [tz] America/Santa_Isabel

And in today's final listen, XEQIN announced "cinco de la tarde con veinticuatro minutos" (literally "5 of the afternoon with 24 minutes") at about 8:24 PM USEST--the same as 5:24 PM USPST. At least this year, San Quintín seems to have followed has followed US rules.

So much for that bookmark.

    @dashdashado

On Sat, Oct 31, 2015 at 10:12 PM, Arthur David Olson <arthurdavidolson@gmail.com> wrote:

This evening's next-to-last listen to XEQIN included advice to listeners to "atrarse una hora de su reloj" ("delay your clock by an hour") tonight before going to bed. The end-of-broadcast-day national anthem, due at 7:00 p. m. local time, came shortly after 10:00 p.m. USEDT, consistent with San Quintín still being on daylight saving time.

The last listen should be tomorrow or Monday evening.

    @dashdashado

On Tue, Oct 27, 2015 at 3:44 PM, Matt Johnson <mj1856@hotmail.com> wrote:

Acknowledged.  Thanks for the clarification.

-Matt

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From: Paul Eggert
Sent: 10/27/2015 10:31 AM
To: Matt Johnson
Cc: Time Zone Mailing List
Subject: Re: [tz] America/Santa_Isabel

Matt Johnson wrote:
> there is a corresponding entry in Windows,  "Pacific Standard Time (Mexico) |(UTC-08:00) Baja California"

I'm afraid this will have to be adjusted on the Microsoft end. There needs to be
a procedure for removing time zones that turn out to be mistakes.
America/Santa_Isabel is a mistake, and I suppose we can view this as an
opportunity for ironing out any procedural glitches while removing it. We do
have a backward compatibility link on the tzdata side; perhaps that will help
for the Microsoft side.

> Also, there's a chance that San Quintin could indeed start using Mexican DST rules in 2017,

We can create a zone America/San_Quintin if that happens.