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geonames.org mishandles north Vietnam time zones before 1975  XML
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eggert



Joined: 29/06/2020 00:00:13
Messages: 2
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In "[tz] North Vietnam 1970 to 1975 - Asia/Hanoi belongs into main file" <https://mm.icann.org/pipermail/tz/2020-June/029136.html> Alois Triendl writes:
The public geonames.org database assigns the zone Asia/Ho_Chi_Minh for all location in country VN (Vietnam). 
This assignment is incorrect, as tzdb's Asia/Ho_Chi_Minh entry corresponds only to locations in Vietnam that observed South Vietnam's time zone rules from 1970 through 1975. The Vietnam locations that observed North Vietnam's rules during that period should be marked with Asia/Bangkok instead.

Who's responsible for maintaining this part of the geonames.org database and how can I report the bug to them?

Thanks.
marc



Joined: 08/12/2005 07:39:47
Messages: 4412
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Hi Paul

Thanks for reaching out.

I have seen the thread on the timezone mailing list and thought like Alois did that this is a bug in the tzdb.

Bangkok stands for Thailand and cannot be used for cities in Vietnam. At least this is how I understand the tzdb rules.
If the countrycode is irrelevant why do we have two entries for Germany for instance?
For Germany we have "Europe/Berlin" and "Europe/Busingen". The later stands for a small enclave village surrounded by Switzerland and always followed the Swiss rules.

To me it is clear we cannot use Asia/Bangkok for locations in other counties than Thailand.



Best Regards

Marc

[WWW]
eggert



Joined: 29/06/2020 00:00:13
Messages: 2
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Bangkok stands for Thailand and cannot be used for cities in Vietnam. At least this is how I understand the tzdb rules.  

That understanding is incorrect. Asia/Bangkok stands for a region that includes Thailand, Cambodia, Laos, and the northern part of Vietnam. Similarly, Europe/Zurich stands for Switzerland, Liechtenstein, and the Büsingen am Hochrhein enclave (part of Germany).

Formerly, tzdb always created Link entries for this sort of thing. These Link entries were a hassle to maintain, partly for political reasons, and so tzdb no longer does this when we discover a new instance of this situation. Since we discovered the situation for northern Vietnam after the tzdb procedure change, we did not create a Link entry for it. We keep old Link entries (such as for Europe/Busingen) only for backward compatibility.

So this is not a bug in tzdb, it's a bug in geonames.

Please see Steffen Thorsen's recent email to the tz list https://mm.icann.org/pipermail/tz/2020-July/029154.html for how timeanddate.com is fixing its time zone database to account for this situation.
marc



Joined: 08/12/2005 07:39:47
Messages: 4412
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ok, the timezoneid for the northern Part of Vietnam has been changed to Asia/Bangkok and will be available in tomorrows extracts.

Thanks for the report.

I think it is a pitty tzdb no longer creates these backlinks. It was an important piece of information which will be lost in the future. If the information is no longer available in structured data then it will have to be included in the comments which will also lead to discussions and more ambiguity and uncertainty.
Timezones are inherently a political construct and political discussions cannot be completely avoided.

Best Regards

Marc

[WWW]
falcon78



Joined: 31/03/2023 15:47:04
Messages: 1
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Hello,

this change appears to have a side effect in the timezone api. The API returns that north Vietnam belongs to Thailand:
Code:
 <geonames>
 <timezone tzversion="tzdata2022g">
 <countryCode>TH</countryCode>
 <countryName>Thailand</countryName>
 <lat>21.22166667</lat>
 <lng>105.80555556</lng>
 <timezoneId>Asia/Bangkok</timezoneId>
 <dstOffset>7.0</dstOffset>
 <gmtOffset>7.0</gmtOffset>
 <rawOffset>7.0</rawOffset>
 <time>2023-03-31 20:39</time>
 <sunrise>2023-03-31 05:51</sunrise>
 <sunset>2023-03-31 18:11</sunset>
 </timezone>
 </geonames>
 

Is it intended that the country field is the one of the timezone and not the country of the coordinates?
 
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