[tz] Did Greenland abolish daylight saving from 2024 on?

Paul Eggert eggert at cs.ucla.edu
Fri Nov 17 08:06:43 UTC 2023

On 2023-11-16 19:35, Guy Harris wrote:
> On Nov 16, 2023, at 6:29 PM, Paul Eggert <eggert at cs.ucla.edu> wrote:

> ...which means that the phrase "Daylight Savings Time" in the POSIX standard refers to something that's not exactly the same as "daylight saving time" as generally understood, i.e. it doesn't necessarily mean "the time that's in effect during summer and possibly some close-to-summer dates in spring and autumn, if clocks are adjusted twice a year, with the clock setting during summer and blah blah blah being ahead of the clock setting during the rest of the year".

If you're accustomed to the United States then that's indeed what 
"daylight saving time" has meant. And given the US's influence it's not 
surprising that the usage is common elsewhere. However, it's not 
universal, and POSIX and TZDB support the more-general case.

The earliest use of negative DST that's recorded in TZDB is 
Czechoslovakia during winter 1946/1947. That's also the earliest use 
recorded in the Wikipedia page on negative DST 
<https://en.wikipedia.org/wiki/Winter_time_(clock_lag)> - a page that 
you've edited. I would not be surprised if negative DST was used 
somewhere even before 1946 but we don't know about it, as records before 
1970 are so woefully incomplete.

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