1 # Allowance for leap seconds added to each time zone file.
3 # This file is in the public domain.
5 # This file is generated automatically from the data in the public-domain
6 # NIST format 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 # The NIST file is used instead of its IERS upstream counterpart
10 # <https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list>
11 # because under US law the NIST file is public domain
12 # whereas the IERS file's copyright and license status is unclear.
13 # For more about leap-seconds.list, please see
14 # The NTP Timescale and Leap Seconds
15 # <https://www.eecis.udel.edu/~mills/leap.html>.
17 # The rules for leap seconds are specified in Annex 1 (Time scales) of:
18 # Standard-frequency and time-signal emissions.
19 # International Telecommunication Union - Radiocommunication Sector
20 # (ITU-R) Recommendation TF.460-6 (02/2002)
21 # <https://www.itu.int/rec/R-REC-TF.460-6-200202-I/>.
22 # The International Earth Rotation and Reference Systems Service (IERS)
23 # periodically uses leap seconds to keep UTC to within 0.9 s of UT1
24 # (a proxy for Earth's angle in space as measured by astronomers)
25 # and publishes leap second data in a copyrighted file
26 # <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>.
27 # See: Levine J. Coordinated Universal Time and the leap second.
28 # URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995
29 # <https://ieeexplore.ieee.org/document/7909995>.
31 # There were no leap seconds before 1972, as no official mechanism
32 # accounted for the discrepancy between atomic time (TAI) and the earth's
33 # rotation. The first ("1 Jan 1972") data line in leap-seconds.list
34 # does not denote a leap second; it denotes the start of the current definition
37 # All leap-seconds are Stationary (S) at the given UTC time.
38 # The correction (+ or -) is made at the given time, so in the unlikely
39 # event of a negative leap second, a line would look like this:
40 # Leap YEAR MON DAY 23:59:59 - S
41 # Typical lines look like this:
42 # Leap YEAR MON DAY 23:59:60 + S
43 Leap 1972 Jun 30 23:59:60 + S
44 Leap 1972 Dec 31 23:59:60 + S
45 Leap 1973 Dec 31 23:59:60 + S
46 Leap 1974 Dec 31 23:59:60 + S
47 Leap 1975 Dec 31 23:59:60 + S
48 Leap 1976 Dec 31 23:59:60 + S
49 Leap 1977 Dec 31 23:59:60 + S
50 Leap 1978 Dec 31 23:59:60 + S
51 Leap 1979 Dec 31 23:59:60 + S
52 Leap 1981 Jun 30 23:59:60 + S
53 Leap 1982 Jun 30 23:59:60 + S
54 Leap 1983 Jun 30 23:59:60 + S
55 Leap 1985 Jun 30 23:59:60 + S
56 Leap 1987 Dec 31 23:59:60 + S
57 Leap 1989 Dec 31 23:59:60 + S
58 Leap 1990 Dec 31 23:59:60 + S
59 Leap 1992 Jun 30 23:59:60 + S
60 Leap 1993 Jun 30 23:59:60 + S
61 Leap 1994 Jun 30 23:59:60 + S
62 Leap 1995 Dec 31 23:59:60 + S
63 Leap 1997 Jun 30 23:59:60 + S
64 Leap 1998 Dec 31 23:59:60 + S
65 Leap 2005 Dec 31 23:59:60 + S
66 Leap 2008 Dec 31 23:59:60 + S
67 Leap 2012 Jun 30 23:59:60 + S
68 Leap 2015 Jun 30 23:59:60 + S
69 Leap 2016 Dec 31 23:59:60 + S
71 # UTC timestamp when this leap second list expires.
72 # Any additional leap seconds will come after this.
73 # This Expires line is commented out for now,
74 # so that pre-2020a zic implementations do not reject this file.
75 #Expires 2021 Dec 28 00:00:00
77 # POSIX timestamps for the data in this file:
78 #updated 1467936000 (2016-07-08 00:00:00 UTC)
79 #expires 1640649600 (2021-12-28 00:00:00 UTC)
81 # Updated through IERS Bulletin C61
82 # File expires on: 28 December 2021