<html><head></head><body><div class="ydpbbfbbfebyahoo-style-wrap" style="font-family: Helvetica Neue, Helvetica, Arial, sans-serif !important; font-size: 16px;"><div id="ydpbbfbbfebyiv4065565996"><div><div style="font-family: Helvetica Neue, Helvetica, Arial, sans-serif !important; font-size: 16px;" class="ydpbbfbbfebyiv4065565996ydp9d087972yahoo-style-wrap"><div dir="ltr"><div dir="ltr" class="ydpbbfbbfebyiv4065565996ydp937fa193pasted-link"><div>Hello,</div><div><br></div>Sources about time zones in Mongolia
seem to list one of two conflicting configurations. The first
configuration, mentioned in a comment to the TZ database in 1999, citing
a Mongolian government website, lists the provinces of Bayan-Ölgii,
Khovd and Uvs in UTC+7, and the rest of the country in UTC+8. The second
configuration, mentioned in a comment to the database in 2001, lists
Bayan-Ölgii, Khovd, Uvs, Govi-Altai and Zavkhan in UTC+7, Dornod and
Sükhbaatar in UTC+9, and the rest of the country in UTC+8.<br><br>The first configuration is still mentioned by several Mongolian travel agencies:<br><a href="https://www.adventurerider.mn/en/page/about_mongolia" rel="nofollow" target="_blank">https://www.adventurerider.mn/en/page/about_mongolia</a> <br><a href="http://www.naturetours.mn/nt/mongolia.php" rel="nofollow" target="_blank">http://www.naturetours.mn/nt/mongolia.php</a> <br><a href="https://www.newjuulchin.mn/web/content/7506?unique=fa24a0f6e96e022a3578ee5195ac879638c734ce" rel="nofollow" target="_blank">https://www.newjuulchin.mn/web/content/7506?unique=fa24a0f6e96e022a3578ee5195ac879638c734ce</a> <br><br>It also matches these flight schedules in 2013:<br><a href="http://web.archive.org/web/20130722023600/https://www.hunnuair.com/en/timetabled" rel="nofollow" target="_blank">http://web.archive.org/web/20130722023600/https://www.hunnuair.com/en/timetabled</a> <br>The
flight times imply that the airports of Uliastai (Zavkhan), Choibalsan
(Dornod) and Altai (Govi-Altai) are in the same time zone as
Ulaanbaatar, and Khovd is one hour behind.<br><br>It also matches a Mongolian news article about the election in 2017:<br><a href="https://mongolia.gogo.mn/r/806d6" rel="nofollow" target="_blank">https://mongolia.gogo.mn/r/806d6</a> <br><br>The second configuration was mentioned by an official of the Mongolian standards agency in an interview in 2014:<br><a href="https://ikon.mn/n/9v6" rel="nofollow" target="_blank">https://ikon.mn/n/9v6</a> <br><br>And it's still listed by the Mongolian aviation agency:<br> <div><a href="https://ais.mn/files/aip/eAIP/2023-12-25/html/eSUP/ZM-eSUP-23-04-en-MN.html" rel="nofollow" target="_blank">https://ais.mn/files/aip/eAIP/2023-12-25/html/eSUP/ZM-eSUP-23-04-en-MN.html</a> </div><br>The
TZ database used the first configuration until 2001, when it switched
to the second configuration, under the assumption that its sources were
more reliable. In 2008, based on sources indicating that Choibalsan
actually used UTC+8, the database changed Dornod and Sükhbaatar to
UTC+8, but only from 2008 on, and maintained Govi-Altai and Zavkhan in
UTC+7. This resulted in a mix of the two configurations that is not
supported as a whole by any source.<br><br>Based on all the above
sources, I believe that the first configuration is what is actually
observed in Mongolia and has been so all along, at least since 1999. The
second configuration closely matches the ideal time zone boundaries at
97.5°E and 112.5°E but it doesn't seem to be used in practice. So I
suggest the following:<br>1. In zone.tab, remove Govi-Altai and Zavkhan
from Asia/Ulaanbaatar, assuming that they have always used the same time
as Ulaanbaatar, or create a new zone Asia/Uliastai showing Govi-Altai
and Zavkhan in UTC+8 since at least 1999.<br><div>2. Remove the zone
Asia/Choibalsan or make it an alias of Asia/Ulaanbaatar, assuming that
it has always used the same time as Ulaanbaatar, or list its change from
UTC+9 to UTC+8 since at least 1999 instead of 2008.</div><div><br></div><div dir="ltr">Regards,</div>Dave</div></div></div></div></div></div><div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br><table style="border-top: 1px solid #D3D4DE;"><tr><td style="width: 55px; padding-top: 13px;"><a href="http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail" target="_blank"><img src="https://s-install.avcdn.net/ipm/preview/icons/icon-envelope-tick-green-avg-v1.png" alt="" width="46" height="29" style="width: 46px; height: 29px;"></a></td><td style="width: 470px; padding-top: 12px; color: #41424e; font-size: 13px; font-family: Arial, Helvetica, sans-serif; line-height: 18px;">Virus-free.<a href="http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail" target="_blank" style="color: #4453ea;">www.avg.com</a></td></tr></table><a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"></a></div></body></html>