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

Steve Allen sla at ucolick.org
Mon Apr 26 22:36:32 UTC 2021

On Mon 2021-04-26T17:57:57-0400 John Sauter via tz hath writ:
> If you try to convert the PTP integer into civil time for display
> purposes, you need to deal with the values 15,638,408 and 47,174,409.
> These correspond to the two leap seconds between 1970 and 1972 in Tony
> Finch's table: June 30, 1970 and June 30, 1971 at 23:59:60 UTC.

Except in Germany, and anywhere nearby where folks set clocks using DCF77:

UTC (old) as determined by DHI was broadcast at
7h, 10h except Sunday
19h, 19h30m, 20h, 21h, 22h, 23h, 0h, 1h, 2h except Saturday and Sunday
1h and 2h only between March 1 and October 31

SAT as determined by PTB was broadcast at
 6h11m to  6h59m
 7h30m to  9h59m
10h30m to 10h59m
and between minutes 11 and 29, 41 and 59 of every hour from
19h11m to  5h59m

so that table of POSIX offset time depends on when you were listening
to the radio to set your clock.

And in China neither of the above systems.

This was for 1970-01-01.
Farther back in time the chaos was worse.

Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street               Voice: +1 831 459 3046         Lng -122.06015
Santa Cruz, CA 95064           https://www.ucolick.org/~sla/  Hgt +250 m

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