[tz] JavaScript IANA date/time library, now with support for leap seconds, TAI, TDT

Tony Finch dot at dotat.at
Mon Apr 26 23:55:56 UTC 2021

Paul Gilmartin via tz <tz at iana.org> wrote:
> Doesn't TAI use the Gregorian calendar, so
> 2017:01:01t00:00:00 TAI is
> 2016:12:31t23:59:23 UTC.  That's just a timezone convention
> -- the date may differ among various timezones.

Not "just", I'm afraid. When a timezone changes offset (e.g. to or from
DST) the periods with different offsets follow directly one after the
other. So, to avoid ambiguity when the clocks go back, you need to write
down both the time and the offset.

But when DTAI changed from 36 to 37 there was a one second gap, the leap
second 2016-12-31 23:59:60. Instead of including a DTAI offset in the
time, we disambiguate with a special :60 second.

f.anthony.n.finch  <dot at dotat.at>  https://dotat.at/
Cape Wrath to Rattray Head including Orkney: East or northeast 4 or 5,
occasionally 6 at first. Slight or moderate. Showers. Good.

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