On Tue 2023-01-17T17:56:17-0700 Paul Gilmartin via tz hath writ:
I have not experimented with TZ=right/* for dates prior to 1972. <http://leapsecond.com/java/gpsclock.htm>
IBM should assume no leap seconds, but because the old UTC frequency offset between 1970 and 1972 was 300e-10 that means at 1970 the difference TAI-UTC was 8.000082 s as shown in https://www.ucolick.org/~sla/leapsecs/deltat.html#amscidelt.png "right" timezones assume a unix system clock which was TAI - 10 s at 1970 and that SI seconds have been counted since at 1970, but that is not how people actually set their clocks. -- 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