1287020Sdelphij# Allowance for leap seconds added to each time zone file. 2267460Sedwin 3287020Sdelphij# This file is in the public domain. 42742Swollman 5287020Sdelphij# This file is generated automatically from the data in the public-domain 6352354Sphilip# NIST format leap-seconds.list file, which can be copied from 7339630Sphilip# <ftp://ftp.nist.gov/pub/time/leap-seconds.list> 8352354Sphilip# or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>. 9368822Sphilip# The NIST file is used instead of its IERS upstream counterpart 10368822Sphilip# <https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list> 11368822Sphilip# because under US law the NIST file is public domain 12368822Sphilip# whereas the IERS file's copyright and license status is unclear. 13287020Sdelphij# For more about leap-seconds.list, please see 14287020Sdelphij# The NTP Timescale and Leap Seconds 15339630Sphilip# <https://www.eecis.udel.edu/~mills/leap.html>. 16287020Sdelphij 17352354Sphilip# The rules for leap seconds are specified in Annex 1 (Time scales) of: 18352354Sphilip# Standard-frequency and time-signal emissions. 19352354Sphilip# International Telecommunication Union - Radiocommunication Sector 20352354Sphilip# (ITU-R) Recommendation TF.460-6 (02/2002) 21352354Sphilip# <https://www.itu.int/rec/R-REC-TF.460-6-200202-I/>. 22352354Sphilip# The International Earth Rotation and Reference Systems Service (IERS) 23287020Sdelphij# periodically uses leap seconds to keep UTC to within 0.9 s of UT1 24352354Sphilip# (a proxy for Earth's angle in space as measured by astronomers) 25339630Sphilip# and publishes leap second data in a copyrighted file 26339630Sphilip# <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>. 27339630Sphilip# See: Levine J. Coordinated Universal Time and the leap second. 28325159Sphilip# URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995 29339630Sphilip# <https://ieeexplore.ieee.org/document/7909995>. 30342668Sphilip 31352354Sphilip# There were no leap seconds before 1972, as no official mechanism 32352354Sphilip# accounted for the discrepancy between atomic time (TAI) and the earth's 33352354Sphilip# rotation. The first ("1 Jan 1972") data line in leap-seconds.list 34342668Sphilip# does not denote a leap second; it denotes the start of the current definition 35342668Sphilip# of UTC. 362742Swollman 37352354Sphilip# All leap-seconds are Stationary (S) at the given UTC time. 38352354Sphilip# The correction (+ or -) is made at the given time, so in the unlikely 39352354Sphilip# event of a negative leap second, a line would look like this: 40352354Sphilip# Leap YEAR MON DAY 23:59:59 - S 41352354Sphilip# Typical lines look like this: 42352354Sphilip# Leap YEAR MON DAY 23:59:60 + S 432742SwollmanLeap 1972 Jun 30 23:59:60 + S 442742SwollmanLeap 1972 Dec 31 23:59:60 + S 452742SwollmanLeap 1973 Dec 31 23:59:60 + S 462742SwollmanLeap 1974 Dec 31 23:59:60 + S 472742SwollmanLeap 1975 Dec 31 23:59:60 + S 482742SwollmanLeap 1976 Dec 31 23:59:60 + S 492742SwollmanLeap 1977 Dec 31 23:59:60 + S 502742SwollmanLeap 1978 Dec 31 23:59:60 + S 512742SwollmanLeap 1979 Dec 31 23:59:60 + S 522742SwollmanLeap 1981 Jun 30 23:59:60 + S 532742SwollmanLeap 1982 Jun 30 23:59:60 + S 542742SwollmanLeap 1983 Jun 30 23:59:60 + S 552742SwollmanLeap 1985 Jun 30 23:59:60 + S 562742SwollmanLeap 1987 Dec 31 23:59:60 + S 572742SwollmanLeap 1989 Dec 31 23:59:60 + S 582742SwollmanLeap 1990 Dec 31 23:59:60 + S 592742SwollmanLeap 1992 Jun 30 23:59:60 + S 602742SwollmanLeap 1993 Jun 30 23:59:60 + S 612742SwollmanLeap 1994 Jun 30 23:59:60 + S 6239871SphkLeap 1995 Dec 31 23:59:60 + S 6339871SphkLeap 1997 Jun 30 23:59:60 + S 6439898SphkLeap 1998 Dec 31 23:59:60 + S 65147771SphkLeap 2005 Dec 31 23:59:60 + S 66181424SedwinLeap 2008 Dec 31 23:59:60 + S 67233445SedwinLeap 2012 Jun 30 23:59:60 + S 68287020SdelphijLeap 2015 Jun 30 23:59:60 + S 69307361SbaptLeap 2016 Dec 31 23:59:60 + S 70267460Sedwin 71360362Sphilip# UTC timestamp when this leap second list expires. 72360362Sphilip# Any additional leap seconds will come after this. 73360362Sphilip# This Expires line is commented out for now, 74360362Sphilip# so that pre-2020a zic implementations do not reject this file. 75369144Sgit2svn#Expires 2021 Dec 28 00:00:00 76360362Sphilip 77339630Sphilip# POSIX timestamps for the data in this file: 78352354Sphilip#updated 1467936000 (2016-07-08 00:00:00 UTC) 79369144Sgit2svn#expires 1640649600 (2021-12-28 00:00:00 UTC) 80339630Sphilip 81369144Sgit2svn# Updated through IERS Bulletin C61 82369144Sgit2svn# File expires on: 28 December 2021 83