On Fri 2016-12-30T20:20:57 +0000, Poul-Henning Kamp hath writ: > >It may prove useful to know why the POSIX Working Group (WG) excluded > >leap seconds, in their own words. > > POSIX didn't "exclude leap seconds", they chose not to "add leap seconds".
In the 1988 standard it is clear that they chose not to add the century leap-year rule. They preferred simplicity for now rather than correctness over an interval longer than time_t could then encode. But the archives of the tz project show that it was well underway at the time of the 1986 draft and that Bradley White had created the leap second handling code in tz before the voting on the 1988 standard. Landon Curt Noll is listed in the 1988 standard as one of the members and he reported that POSIX knew that yet chose to exclude leap seconds. https://www.mail-archive.com/leapsecs@rom.usno.navy.mil/msg00109.html POSIX chose not to attempt precise time. Anyone trying to do precise time with POSIX is implementing an extension to the standard. There is much more record of the consternation over the handling of time zones in the 1988 standard. The end result of time zones in the 1988 standard was that POSIX did not require full handling of the complexity of civil time, but POSIX did allow extensions that do correctly handle civil time. In contrast, the end result for leap seconds is that POSIX did not require handling of leap seconds, and that it explicitly prohibited their correct handling unless an implementation violates some aspect of POSIX -- pick which aspect, and everybody chose a different one. -- Steve Allen <s...@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 http://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs