[tz] permanent DST and North American time zone names

Max Harmony maxh at maxh.name
Wed Mar 16 07:43:09 UTC 2022

On 16 Mar 2022, at 00.45, Chris Walton via tz <tz at iana.org> wrote:
> 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 would consider these options incorrect. While the bill is being called "permanent DST" (even in its own section heading), the actual implementation eliminates DST and defines all time zones as one hour earlier.

> 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.

I'm not familiar with the Canadian Interpretation Act, but I think you're referring to its definition of standard time? I would expect Canada to make the same change if the US does it first. Canada has followed previous US changes to DST, and it seems like the main reason they haven't done this already is to keep the same time zones as the US.

On 16 Mar 2022, at 02.26, Ephraim Silverberg via tz <tz at iana.org> wrote:
> Another option would be to just delete the middle letter and use two-letter abbreviations -- e.g.  EST/EDT -> ET

Let's call this option 4b. I like the idea; there's no need to specify it's a standard time when that's the only kind it can be. It does seem like a slight change from its current meaning, though (something happening at the same time regardless of whether DST is in effect vs. the only time zone used in the region). I can't think of any reason that would matter, but it seems like exactly the sort of subtle distinction that breaks things. Of course, the ?ST names having a different meaning than they used to could *also* break things.

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