[tz] tzdb timezone names/identifiers and links (was: Add new timezone for Hanoi Capital, Vietnam)
Michael H Deckers
michael.h.deckers at googlemail.com
Tue Feb 19 21:09:52 UTC 2019
On 2019-02-19 19:35, Steve Allen wrote:
> The scope of IANA tzdb is, in short, to provide a way for POSIX-like
> systems to convert between internal system clock time_t values and
> local civil time in a way where a single choice is valid for all
> history since 1970. This is reasonably well documented.
Regardless how well tzdb is documented, one cannot say that
tzdb data is very systematic. Compare the case of Asia/Hanoi
with that of Europe/Busingen.
Europe/Busingen was introduced into tzdb on 2013-02-27; it
differs from Europe/Berlin since 1970, but it agrees with
Europe/Zurich and was linked to it ever since.
Only five years later, Asia/Hanoi was added to backzone; it
differs from Asia/Ho_Chi_Minh since 1970, but agrees with
Asia/Bangkok since 1955.
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?
It may well be that some changes in the theory file can be
construed to explain the discrepancy, but I think that database
data should reflect the current design principles, not
their history. I may be a sloppy reader, but I do see what
the theory.html file says about the two questions above.
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