[tz] Yukon to move to year-round PDT

Chris Walton Chris.Walton at telus.com
Fri Mar 6 05:44:19 UTC 2020


> From: tz <tz-bounces at iana.org> On Behalf Of Paul.Koning at dell.com
> > On Mar 5, 2020, at 8:45 PM, Paul Eggert <eggert at cs.ucla.edu> wrote:
> >
> >
> > [EXTERNAL EMAIL]
> > On 3/5/20 5:31 PM, Paul Goyette wrote:
> >> Doesn't such a position, however, fly in the face of the "boots on
> >> the ground" approach we've taken in other situations?
> >
> > Yes it does. But then, we consistently flew in the face of that
> > approach in the past when this situation arose, so at least we'd be
> > *consistently* inconsistent. (There is a technical obstacle to having
> > a time zone observe DST indefinitely, as this can't be implemented via
> > POSIX TZ strings on many platforms.)
> >
> > Another possibility would be to put "-07" into the database for now, until
> we find out what abbreviation (if any) people actually use once the
> timestamps diverge in November. If people end up using "PDT" next winter
> in Yukon we can put that into the database, even though it will be odd that
> it's "PDT" even though the is_dst flag will be 0 due to the abovementioned
> technical obstacle.
> >
> > I've been fearing this technical snafu for many months as the "permanent
> DST" movement has gained steam in North America.
> 
> I view isdst as valid only if there are two time offsets, active at different times
> according to something resembling a rule.  Normally "isdst" means summer
> time, with one or two oddball exceptions.  But when only one rule is in effect
> year-round, it doesn't make sense to set the "non-standard" flag, which is
> what "isdst" is.
> 
> So never mind the "technical obstacle"; set is_dst 0 as a matter of principle
> no matter whether POSIX justifies it or not.

I think everyone is in agreement on setting is_dst to 0.  Good.

I don't agree with the idea of using "-07" as the time zone abbreviation with a "wait and see" approach.
I fear it would lead to legibility problems in such places as weather forecasts.
E.g. notice how the current time zone abbreviation is prominently displayed in a time stamp on Environment Canada's weather forecast pages for Dawson City YT and Fort Nelson BC.
 https://weather.gc.ca/city/pages/yt-6_metric_e.html
 https://weather.gc.ca/city/pages/bc-83_metric_e.html.
I would be very surprised if these pages did not pull the time zone abbreviations directly from tzdata time zone files.
The current time stamp of "8:00 PM MST Thursday 5 March 2020" is very clear and very readable.
If the same time stamp were to show up as "8:00 PM -07 Thursday 5 March 2020", I would consider it to be confusing to the average Canadian.

And I still don't agree with the idea of using "PDT" even though it would align with the Yukon government's press release.
We have to consider that:
America/Dawson_Creek, America/Fort_Nelson, America/Whitehorse, and America/Dawson together form a contiguous area within a single country (Canada).
Starting next Sunday, the entire area will be on permanent UTC-7.
  America/Dawson_Creek has been using the MST time zone abbreviation since 1972.
  America/Fort_Nelson has been using the "MST" time zone abbreviation since 2015.
It would make no sense at all to apply a different time zone abbreviation (either "-07" or "PDT") to America/Dawson or America/Whitehorse; doing so would create a permanent confusion and inconsistency that would never go away.  If we stick with "MST" there may be a few people that are confused for a few days, but that confusion will quickly pass.

-chris






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