[tz] Ethiopia local time

Tim Parenti tim at timtimeonline.com
Fri Oct 5 22:52:36 UTC 2018


Sure, but the notion of "wall-clock midnight" under year-round +6 DST is no
more or less tied to actual solar midnight than for any other zone as they
exist today.  As Steve puts it, hour 00 just represents the hour at which
the calendar date changes.

In your extreme example, it may seem odd to say it's midnight when the sun
is still setting — and I'm certainly not suggesting Ethiopians would
actually do anything remotely similar  But these discrepancies don't stop
folks from referring to 00:00 local time as "midnight" in most of the cases
we cover, even if it… well… isn't.

Moreover, we already make explicit this convention (tying hour 00 to the
Western cultural notion of "midnight") elsewhere:
https://github.com/eggert/tz/blob/b709eb84eaa48354186d4a11c86395e399f19c12/zic.8#L281-L282

Again, I won't be bothered if it's left out, but I also haven't really seen
any reason against such a clarification.  Perhaps my proposed wording is
not the best.

--
Tim Parenti


On Thu, 4 Oct 2018 at 23:49, Phake Nick <c933103 at gmail.com> wrote:

> That's not really the case. If some country decided to actually implement
> a year-round +6 DST, then that would also be included in tz database
>
>  2018-10-5 07:48, Tim Parenti <tim at timtimeonline.com> wrote:
>
>> For tz's purposes, though (the sentence begins "The tz database models
>> time using…"), those are synonymous.  Of course, this may not be the case
>> if you're using a workaround like the one suggested for Ethiopia, but the
>> goal is to further clarify that that's out of our scope.
>>
>> --
>> Tim Parenti
>>
>>
>> On Thu, 4 Oct 2018 at 19:14, Steve Allen <sla at ucolick.org> wrote:
>>
>>> On Thu 2018-10-04T18:13:56-0400 Tim Parenti hath writ:
>>> > To bring this back, then, to a recognition of the potential
>>> differences in
>>> > how the hours are counted, we should probably expand the text in theory
>>> > slightly to specify that tz counts hours under the assumption that 00
>>> > represents midnight.
>>>
>>> I think that 00 represents the hour at which the calendar day and date
>>> change.  That may not happen in the middle of the night.
>>>
>>> --
>>> Steve Allen                    <sla at ucolick.org>              WGS-84
>>> (GPS)
>>> UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat
>>> +36.99855
>>> 1156 High Street               Voice: +1 831 459 3046         Lng
>>> -122.06015
>>> Santa Cruz, CA 95064           http://www.ucolick.org/~sla/   Hgt +250 m
>>>
>>
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