[tz] Was there a 1971-12-31 23:59:60?
Paul Gilmartin
PaulGBoulder at aim.com
Sat Nov 10 05:04:35 UTC 2018
Hello, Judah Levine,
I get unexpected results on Linux with TZ=right/Universal.
I downloaded https://data.iana.org/time-zones/releases/tzdata2018g.tar.gz
to try to find an explanation. There, I find,
in: leap-seconds.list
...
#
# Updated through IERS Bulletin C56
# File expires on: 28 June 2019
#
#@ 3770668800
#
2272060800 10 # 1 Jan 1972
2287785600 11 # 1 Jul 1972
2303683200 12 # 1 Jan 1973
2335219200 13 # 1 Jan 1974
2366755200 14 # 1 Jan 1975
...
I tend to believe this, but in: leapseconds
...
# There were no leap seconds before 1972, because the official mechanism
# accounting for the discrepancy between atomic time and the earth's rotation
# did not exist.
# The correction (+ or -) is made at the given time, so lines
# will typically look like:
# Leap YEAR MON DAY 23:59:60 + R/S
# or
# Leap YEAR MON DAY 23:59:59 - R/S
# If the leap second is Rolling (R) the given time is local time (unused here).
Leap 1972 Jun 30 23:59:60 + S
Leap 1972 Dec 31 23:59:60 + S
Leap 1973 Dec 31 23:59:60 + S
Leap 1974 Dec 31 23:59:60 + S
...
Well, it's consistent with itself. 1971-12-31 23:59:60 is *before*
1972. But "leap-seconds.list" shows one more leap second that "leapseconds".
I'm confused.
Thanks,
gil
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