[tz] tzdb timezone names/identifiers and links (was: Add new timezone for Hanoi Capital, Vietnam)

Tim Parenti tim at timtimeonline.com
Tue Feb 19 21:22:16 UTC 2019

On Tue, 19 Feb 2019 at 15:27, Guy Harris <guy at alum.mit.edu> wrote:

> Maybe this is *another* case where "some applications "misuse" tzdb
> identifiers" and where it might "be better to solve this on a more general
> level such as geo-location<=>timezone mappings", e.g. a meeting date
> shouldn't be tagged with {date/time, tzdb identifier} but with {date/time,
> geographic coordinates}.

Unfortunately, there seems to be a widespread (mistaken) belief that
geographic coordinates are sufficient for deriving the proper tz identifier
in all, or even most cases.  To say nothing of disputed, fluid, and
overlapping territories, folks in actual border communities make all sorts
of *de facto* arrangements as well.

There is a very good reason this project doesn't attempt to define
boundaries, and it's not just an issue of scope, it's an issue of
practicality and tractability.

On Tue, 19 Feb 2019 at 16:10, Michael H Deckers via tz <tz at iana.org> wrote:

>      Why was Europe/Busingen not added to backzone as Asia/Hanoi
>      was? Its history is known very precisely. Why was Asia/Hanoi
>      not added as a link as Europe/Busingen was?

Frankly, it seems it was because when Asia/Hanoi was added to backzone (in
2014, not "five years later" as you write), the opportunity was taken then
and there to change/redefine the rules to avoid scope creep.  Which is all
well and good from a project maintenance standpoint, though I can totally
see why that can seem unfair from a human standpoint.

Had we operated under the rules that existed just before the Hanoi history
was first presented to us, Asia/Hanoi would have had to go into the main
distribution.  The zone-country rules were then deliberately changed to
avoid this (see Laos and Cambodia being coalesced, along with northern
Vietnam, into Asia/Bangkok).  The 2014 submission for Asia/Hanoi was made
in good faith at the time, and while that certainly does not *require* that
a new zone be created, it does feel a little off to effectively have that
potential outcome removed retroactively.

Simply put, Hanoi seems to be the major exception here because it was *the*
zone for which its need was being assessed right at the time when the rules
were being changed.

Tim Parenti
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