[tz] North Vietnam 1970 to 1975 - Asia/Hanoi belongs into main file

Brian Inglis Brian.Inglis at Shaw.ca
Mon Jun 29 04:10:23 UTC 2020

On 2020-06-28 15:22, Alois Treindl wrote:
> On 28.06.20 23:12, Paul Eggert wrote:
>> On 6/28/20 7:42 AM, Alois Treindl wrote:
>>> The public geonames.org database  assigns the zone Asia/Ho_Chi_Minh for all
>>> location in country VN (Vietnam).
>>> This indicates that the comment above is not followed.

>> That's a problem with the geonames.org database, and I suggest reporting
>> the bug to them. The bug should be reported regardless of whether we change
>> tzdb since geonames.org should work with what we have now as well as with
>> what we might have in the future. You can point them at the zone1970.tab
>> file to help explain the situation.
>> A little background here. We don't have the resources to create entries for
>> every location in this part of southeast Asia, with different transition times
>> for when locations changed hands between North and South Vietnam during the
>> 1970-1975 conflict. So we approximate by using Ho Chi Minh as the representative
>> for clocks in south Vietnam, and Bangkok as the representative for clocks in
>> Thailand, Cambodia, Laos and north Vietnam. We have links from Asia/Bangkok to
>> Asia/Phnom_Penh and Asia/Vientiane for backward-compatibility purposes only, as
>> the names Asia/Phnom_Penh and Asia/Vientiane would not exist according to
>> today's guidelines. There's no need for a backward-compatibility link for
>> Asia/Hanoi since that name never existed in tzdb. These are all technical
>> reasons, not political ones.

> I don't agree.
> I think the capital of North Vietnam, Asia/Hanoi should be present in the main
> file, and used.
> Geonames.org will and should not use zones which exist only in backzone and
> will not be compiled by default into binary TZ distributions.> They will and should not use the capital of another country, Bangkok, for
> parts of Vietnam.> In my opinion the case is clear: Hanoi belongs into main file, to cover the
> 1970-1975 period correctly.

Searching for Vietnam time, I see sites stating that Vietnam follows Indochina
Time, so this view does not appear too controversial in the region.
I agree from the design point of view that countries should have their own
independent time zones, as what they do is so unpredictable, and should not be
allowed to affect any other country, so allowing a little judicious duplication
would be in order, where there is no political commonality but only geographical
proximity or coincidence in decision making.

Perhaps the needs of historical communities diverge from those served by the
tzdb project over the issue of differences before 1970.
You could take the experimental github repo, which has history from 1984, or the
tar releases from 1993, and cherry pick which patches to choose to apply, as
Oracle does to improve backward compatibility for its major DB product and Java.
There is absolutely nothing stopping you from creating and distributing your own
patches to tzdata sources, additional source files of rules, zones, and links,
or scripts to patch, build, copy, or link files to meet your historical
community's needs.

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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