[tz] [PATCH 2/3] Replace some zones with links when that doesn't lose non-LMT info.

Stephen Colebourne scolebourne at joda.org
Tue Sep 3 09:33:12 UTC 2013

On 3 September 2013 09:15, Brian Inglis <Brian.Inglis at systematicsw.ab.ca> wrote:
> On 2013-09-03 01:34, Paul Eggert wrote:
>> Link to America/Port_of_Spain instead of having a separate zone
>> that differs only in LMT.  Each LMT entry is just a placeholder for
>> unavailable info, and by itself does not justify a separate zone.
>> Using just one zone simplifies maintenance, makes the runtime
>> a bit smaller, and can help simplify user selection of zones.
>> * southamerica (America/Aruba): Likewise, for America/Curacao.
>> * backward (America/Virgin):
>> * northamerica (America/St_Barthelemy, America/Marigot):
> Folks seem to have forgotten that initial LMT entries contain the Standard
> Time start date, as well as the prior GMTOFF based on longitude of that
> location.
> While I agree that merging zones with different GMTOFF makes no significant
> difference, merging zones with different Standard Time start date loses
> useful historical data, unless the tzdb is seen mainly as a source of DST
> changes since 1970.
> In the changes highlighted below, Standard Time start dates vary from
> 1890-1921, with some different dates in 1911-1912.
> Zones should be merged only if all linked locations have the same Standard
> Time start date, if we wish to maintain the history of when Standard Time
> was established in each time zone.

Yes, unfortunately I agree with Brian.

I note that the patch also changed the observable time-zone
abbreviations (KMT/CMT etc). Again, while this might be invented data,
through existence over a long period it has become undeletable.

As such, most of this patch would need reverting :-(


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