xref: /freebsd/contrib/tzdata/leapseconds (revision 8df8b2d3e51d1b816201d8a1fe8bc29fe192e562)
1# Allowance for leap seconds added to each time zone file.
2
3# This file is in the public domain.
4
5# This file is generated automatically from the data in the public-domain
6# leap-seconds.list file, which can be copied from
7# <ftp://ftp.nist.gov/pub/time/leap-seconds.list>
8# or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>
9# or <ftp://tycho.usno.navy.mil/pub/ntp/leap-seconds.list>.
10# For more about leap-seconds.list, please see
11# The NTP Timescale and Leap Seconds
12# <https://www.eecis.udel.edu/~mills/leap.html>.
13
14# The International Earth Rotation and Reference Systems Service
15# periodically uses leap seconds to keep UTC to within 0.9 s of UT1
16# (which measures the true angular orientation of the earth in space)
17# and publishes leap second data in a copyrighted file
18# <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>.
19# See: Levine J. Coordinated Universal Time and the leap second.
20# URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995
21# <https://ieeexplore.ieee.org/document/7909995>.
22
23# There were no leap seconds before 1972, because the official mechanism
24# accounting for the discrepancy between atomic time and the earth's rotation
25# did not exist.  The first ("1 Jan 1972") data line in leap-seconds.list
26# does not denote a leap second; it denotes the start of the current definition
27# of UTC.
28
29# The correction (+ or -) is made at the given time, so lines
30# will typically look like:
31#	Leap	YEAR	MON	DAY	23:59:60	+	R/S
32# or
33#	Leap	YEAR	MON	DAY	23:59:59	-	R/S
34
35# If the leap second is Rolling (R) the given time is local time (unused here).
36Leap	1972	Jun	30	23:59:60	+	S
37Leap	1972	Dec	31	23:59:60	+	S
38Leap	1973	Dec	31	23:59:60	+	S
39Leap	1974	Dec	31	23:59:60	+	S
40Leap	1975	Dec	31	23:59:60	+	S
41Leap	1976	Dec	31	23:59:60	+	S
42Leap	1977	Dec	31	23:59:60	+	S
43Leap	1978	Dec	31	23:59:60	+	S
44Leap	1979	Dec	31	23:59:60	+	S
45Leap	1981	Jun	30	23:59:60	+	S
46Leap	1982	Jun	30	23:59:60	+	S
47Leap	1983	Jun	30	23:59:60	+	S
48Leap	1985	Jun	30	23:59:60	+	S
49Leap	1987	Dec	31	23:59:60	+	S
50Leap	1989	Dec	31	23:59:60	+	S
51Leap	1990	Dec	31	23:59:60	+	S
52Leap	1992	Jun	30	23:59:60	+	S
53Leap	1993	Jun	30	23:59:60	+	S
54Leap	1994	Jun	30	23:59:60	+	S
55Leap	1995	Dec	31	23:59:60	+	S
56Leap	1997	Jun	30	23:59:60	+	S
57Leap	1998	Dec	31	23:59:60	+	S
58Leap	2005	Dec	31	23:59:60	+	S
59Leap	2008	Dec	31	23:59:60	+	S
60Leap	2012	Jun	30	23:59:60	+	S
61Leap	2015	Jun	30	23:59:60	+	S
62Leap	2016	Dec	31	23:59:60	+	S
63
64# POSIX timestamps for the data in this file:
65#updated 1467936000
66#expires 1561680000
67
68#	Updated through IERS Bulletin C56
69#	File expires on:  28 June 2019
70