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@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