[tz] permanent DST and North American time zone names

Ephraim Silverberg ephraim at cs.huji.ac.il
Wed Mar 16 06:26:35 UTC 2022


Another option would be to just delete the middle letter and use two-letter
abbreviations -- e.g.  EST/EDT -> ET




On Wed, Mar 16, 2022 at 6:47 AM Chris Walton via tz <tz at iana.org> wrote:

> Regardless of what the legislation does or does not say, this database
> needs to quickly adopt a strategy to deal with changes that may be
> necessary for all North American Time zones.
> The supporters and maintainers of this time zone database can take an
> active role in helping to define and endorse a common standard, or they can
> sit back and watch the politicians and the general public fumble the job.
> It would be helpful if there was some collaboration between Microsoft and
> the supporters/maintainers of this database.
>
> I think it is likely that if the US government approves the Sunshine
> Protection Act, that most Canadian provinces and territories will follow
> with similar legislation.
> - British Columbia and Ontario already have the necessary legislation in
> place.
> - Saskatchewan has not changed its clocks in many years.
> - Yukon stopped changing its clocks in 2020.
> - Alberta recently voted to keep the biannual change, it could be the lone
> holdout!
> I admit I have not been following the other Canadian territories and
> provinces closely.
> Also, I have no clue what Mexico, Saint Pierre & Miquelon, or any of the
> small island nations will decide to do.
>
> For this database I can envision four options moving forward:
>
> *Option #1*: ditch the three letter time zone strings and use only
> numerical offsets from UTC.
>  This is a complete cop out that says "Let's abandon our end users and let
> somebody else deal with the issue".  It is my least favorite option.
>   e.g. Los Angeles, Phoenix, and Vancouver:
>         Thu Feb  1 00:00:00 *-07* 2024   (UTC-07)
>         Thu Aug  1 00:00:00 *-07* 2024   (UTC-07)
>   e.g. New York and Toronto:
>         Thu Feb  1 00:00:00 *-04* 2024   (UTC-04)
>         Thu Aug  1 00:00:00 *-04* 2024   (UTC-04)
>
>
> *Option #2*: allow permanent daylight saving
> This could be implemented without too many complications, but it goes
> against the philosophy that daylight saving is an alternate time offset
> that is only used for part of the year.
> This is not my favorite option even though it is probably the least
> disruptive.  I do not think it will make any sense 20 years from now.
>  e.g. Los Angeles, Phoenix, Vancouver, and Whitehorse would be on
> permanent *Pacific Daylight Time*
>         Thu Feb  1 00:00:00 *PDT* 2024   (UTC-07)
>         Thu Aug  1 00:00:00 *PDT* 2024   (UTC-07)
>  e.g. New York and Toronto would be on permanent *Eastern Daylight Time*:
>         Thu Feb  1 00:00:00 *EDT *2024   (UTC-04)
>         Thu Aug  1 00:00:00 *EDT* 2024   (UTC-04)
>
>
> *Option #3*: move most North American entries in the TZ database one zone
> to the east:
> I know we have done this in the past for places such as
> America/Whitehorse, but I expect if we did it for all of Canada and the US
> it would not align with the public's perception of reality.  Also, it
> provides no clear path to deal with any places that are currently using *Atlantic
> Daylight Time (UTC-03)*.
>  e.g. Los Angeles, Phoenix, Vancouver, and Whitehorse would be on
> permanent *Mountain Standard Time*
>         Thu Feb  1 00:00:00 *MST* 2024   (UTC-07)
>         Thu Aug  1 00:00:00 *MST* 2024   (UTC-07)
>  e.g. New York and Toronto would be on permanent *Atlantic Standard Time*:
>         Thu Feb  1 00:00:00 *AST* 2024   (UTC-04)
>         Thu Aug  1 00:00:00 *AST* 2024   (UTC-04)
>
>
> *Option #4*: redefine AKST, PST, MST, CST, EST, AST, and NST to all be
> one hour closer to UTC time.
>  This is currently my preferred option even though it may break some
> software and it is guaranteed to conflict with the Canadian Interpretation
> Act.
>  Alaska Standard Time      (AKST) is redefined to UTC-08.
>  Pacific Standard Time      (PST) is redefined to UTC-07.
>  Mountain Standard Time     (MST) is redefined to UTC-06.
>  Central Standard Time      (CST) is redefined to UTC-05.
>  Eastern Standard Time      (EST) is redefined to UTC-04.
>  Atlantic Standard Time     (AST) is redefined to UTC-03.
>  Newfoundland Standard Time (NST) is redefined to UTC-02:30 (assuming
> Newfoundland abandons the biannual time change)
>   e.g. Los Angeles, Phoenix, Vancouver, and Whitehorse would be on *Pacific
> Standard Time* year-round:
>         Thu Feb  1 00:00:00 *PST* 2024   (UTC-07)
>         Thu Aug  1 00:00:00 *PST* 2024   (UTC-07)
>   e.g. New York and Toronto would be on *Eastern Standard Time*
>  year-round:
>         Thu Feb  1 00:00:00 *EST* 2024   (UTC-04)
>         Thu Aug  1 00:00:00 *EST* 2024   (UTC-04)
>   e.g. Alberta would have to adopt new time zone names:  *Pacific
> Standard Time* in winter, and *Pacific Daylight Time* in summer. (Alberta
> recently voted to keep the biannual clock change).
>         Thu Feb  1 00:00:00 *PST* 2024   (UTC-07)
>         Thu Aug  1 00:00:00 *PDT* 2024   (UTC-06)
>   e.g. Saskatchewan would have to start referring to its time zone name as *Mountain
> Standard Time* instead of *Central Standard Time*. (Saskatchewan has used
> *UTC-06* year-round for many years)
>         Thu Feb  1 00:00:00 *MST* 2024   (UTC-06)
>         Thu Aug  1 00:00:00 *MST* 2024   (UTC-06)
>   e.g. Puerto Rico would have to start referring to its time zone as *Eastern
> Standard Time* instead of *Atlantic Standard Time*.
>         Thu Feb  1 00:00:00 *EST* 2024   (UTC-04)
>         Thu Aug  1 00:00:00 *EST* 2024   (UTC-04)
>   e.g. If Atlantic Canada and Bermuda were to continue changing the clocks
> twice a year, they would be on *Eastern Standard Time* in winter and *Eastern
> Daylight Time* in summer.
>         Thu Feb  1 00:00:00 *EST* 2024   (UTC-04)
>         Thu Aug  1 00:00:00 *EDT* 2024   (UTC-03)
>  e.g. If,  Atlantic Canada and Bermuda were to abandon the time change,
> then they would both end up on *Atlantic Standard Time* year-round.
>         Thu Feb  1 00:00:00 *AST* 2024   (UTC-03)
>         Thu Aug  1 00:00:00 *AST* 2024   (UTC-03)
>
> Did I miss anything?
> -chris
>
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