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zic bug: Wall-clock ordering of transition times
by Tim Parenti Jan. 4, 2021

Jan. 4, 2021

I noticed a bug while incorporating changes to commentary for the Turks and Caicos Islands… https://mm.icann.org/pipermail/tz/2020-December/029609.html Our contemporaneous use of "3:00" in the UNTIL field for the 2018-03-11 change intentionally avoided two clock changes in a row (first from 01:59:59 AST to 01:00:00 EST, then from 01:59:59 EST to 03:00:00 EDT an hour later). https://github.com/eggert/tz/commit/8792d7bed2c684cf842592fd7779645f335a33f6 My recently-added commentary clarifies the reasoning behind this and concludes that the order was likely intended to take effect from 03:00 -04, once the Eastern US had sprung forward, and not at 02:00 -04 as the text suggests. However, I noticed that using "2:00" in the UNTIL field instead doesn't actually result in the expected extra transition: --- to2050.tzs 2020-12-05 14:11:12.000000000 -0500 +++ to2050new.tzs 2020-12-05 14:17:31.000000000 -0500 @@ -5201,7 +5201,7 @@ 2014-03-09 03 -04 EDT 1 2014-11-02 01 -05 EST 2015-03-08 03 -04 AST -2018-03-11 03 -04 EDT 1 +2018-03-11 02 -04 EDT 1 2018-11-04 01 -05 EST 2019-03-10 03 -04 EDT 1 2019-11-03 01 -05 EST It seems that, the 02:00 wall-clock time having already been approached once for the transition out from AST, zic assumes that the transition specified in the US Rule at the same wall-clock time has also taken simultaneous effect in Eastern Time, although in reality it wouldn't yet for another hour. In this case, the wall-clock times of these two transitions are identical, while in actuality the transitions are meant to take effect sequentially. It appears that this bug also manifests in other cases where the strict ordering of transitions does not exactly match the strict ordering of wall-clock times: Trying out "2:30" in the UNTIL field should mean that the Zone transition should happen 30 minutes BEFORE the US Rule would take effect (and thus require two transitions), but by wall-clock time, it would "appear" to be 30 minutes AFTER (fooling zic into thinking only the "latter" Zone transition is needed as the Rule would have "already" taken effect). And, indeed, the results are similarly incorrect here, too: --- to2050.tzs 2020-12-05 14:11:12.000000000 -0500 +++ to2050new.tzs 2020-12-05 14:36:07.000000000 -0500 @@ -5201,7 +5201,7 @@ 2014-03-09 03 -04 EDT 1 2014-11-02 01 -05 EST 2015-03-08 03 -04 AST -2018-03-11 03 -04 EDT 1 +2018-03-11 02:30 -04 EDT 1 2018-11-04 01 -05 EST 2019-03-10 03 -04 EDT 1 2019-11-03 01 -05 EST Certainly an edge case in this particular instance, but given that many historical transitions coincide tightly with transitions in other regions being "joined" or "left", perhaps one worth a further look. -- Tim Parenti

5 16

No Scottish time zone in the 1990s
by Clive D.W. Feather Dec. 30, 2020

Dec. 30, 2020

An interesting (for us on TZ) little bit of history. https://www.bbc.co.uk/news/uk-50950961 "National archives: Sir John Major snubbed separate Scottish time zone" -- Clive D.W. Feather | If you lie to the compiler, Email: clive(a)davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646

1 0

[tz-announce] 2020f release of tz code and data available
by Paul Eggert Dec. 29, 2020

Dec. 29, 2020

The 2020f release of the tz code and data is available, reflecting the following change to the build procedure: 'make rearguard_tarballs' no longer generates a bad rearguard.zi, fixing a 2020e bug. (Problem reported by Deborah Goldsmith.) There are no changes to the data since 2020e. The build-procedure change was circulated on the tz mailing list and is intended for downstream consumers that can process only rearguard format. Please see the PS at the end of this email for more info about rearguard format. Here are links to the release files: https://www.iana.org/time-zones/repository/releases/tzcode2020f.tar.gz https://www.iana.org/time-zones/repository/releases/tzdata2020f.tar.gz https://www.iana.org/time-zones/repository/releases/tzdb-2020f.tar.lz As usual, links to the latest release files are here: https://www.iana.org/time-zones/repository/tzcode-latest.tar.gz https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz Links are also available via plain HTTP, and via FTP from ftp://ftp.iana.org/tz/releases with the same basenames as above. Each release file has a GPG signature, which can be retrieved by appending ".asc" to the above URLs. Copies of these signatures are appended to this message. This release corresponds to commit 846c3ac7abc246094dd754ac6dc90423148a5107 dated 2020-12-29 00:17:46 -0800 and tagged '2020f' in the development GitHub repository at <https://github.com/eggert/tz>. Here are the SHA-512 checksums for the release files: 5f6bf1b508434842eb9dacacc744b5f3375c35b88e401ef372b5fde80ad2f523484fe52a6e99460e402230406ebf6a9261a97efde45a610f8e8085893d55c4ed tzcode2020f.tar.gz dd312def18c807452fda2e697514e2064c5f51ebdbedd0cfe6f231252c76ee5d4409f653b295ed5657b7d30b868690047fdb70a10942e69eaa40b77473e3f9ca tzdata2020f.tar.gz a2efd9cb6308c75de382ff1ddc524dad5da10d76d86c6bf41ab2f979fffae1356b2599b3fcc045eab1cb56b16f9371663da5be57c1f43591517be62e65abbf1c tzdb-2020f.tar.lz Here are the GPG digital signatures for the release files: -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAl/q5ukACgkQ7ZfpDmKq fjSOqA//d2SuaDA9HEXuGXOgTV2f9Iu8x4XF3cIc/UYIh/9yi7T1jVhRD70rPjTO 0g1ohBPoT/oY5OaFholMuZfoIwNgPv2K4c05xNrmNdbbz/3iaddm1zpD5WutRw2c u+hqrR1C5p/ICoSEH+/SAwmBFYEpQYCnkFUScC7YeGoZzzpKls3l/8hvUFaKt8SW ssgS/nVA3L54W8Hdu8WUl2Nz7xmkN3zzRseZMsU3+CrUwXtGzyySZPAJR1Ryk1ee PgwZaoteeGFl08Y7QfvyZBc7xakgnMEdhFB+m2SH//RO6DLjjuWlSAV9wMCk6dZq Uu3yZDVfsV91kiXOavdZFGXQCGXFVmkU7cZnSlpGWuIQGDX0iLOdcuWTFSEw+Av6 UP0cKyX2gJdXaqsYaBpgkCNh0SzG8ui5sS+vimCXG0+0d3z5ru2sHOTSkDxAke6a Jbs5PCz4HXpkIbbE73j+GzaoGWvbzqIledXV+J18uOAcfX13Ejft1nMFyZYh2vvJ 3DH3j1KA0NMs1u9o2F3HWPQcGZKuLFg0BxU2hEeIqbEwXAs980Mo5xrDtFRk4VLy Sg/o6XiREeXV06gXLqlP0vKa+qf88J9u18wMuuiPX1NmNZOcdekVVZtYQ5VhDjbZ xcg3S7YG9HUB+SxnAWQ21jaioQPLYB0Sc2/2vo8VzvIDE9iy8FI= =WeIr -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAl/q5ukACgkQ7ZfpDmKq fjQ8ug//WH7DpYFvSYMKpSj6gG0m5lK0JXcs062EKGQNsVoUjSVImu3VPbpUS9tu cO3NCUmeqTmwhUOuZQN2qGAT2KyNhcLTlza8xuRQm/tJ7SYpArseY9rudQtkjbCi uWELQi5+a6CA/PBBRJzDJwQPTf4wDZr24vDd29tKqBho5T5cisudXHhqh1Bm0Bfr NPyPsS6+oLJofIVsU0I5V+fbnU98ny5I1r/OyVIJgAlvEcb0kMDr0fBfu1dNvJI9 Tyl3kvdLSMCgf/lRXEFYJpI0RuUeIAsOvHaSwSCHKGc7FHzgDiK1U5D/4z5Ipo02 0AQKkLFkEbzwou/5KtX2Q3+yba1AGu64C7elu+aKepUNGhkzAaJrl2xNNM25Sdn4 1WvxOt43GTIze0cr9UHm942sU5UxH0ahv4h9pEbqJ44UVzBhuDDqcMXYJEWhdhMf 6dgRA7SJThuX7tN758to9Ze9XyXMdzAPdJKs/wyLrRGyDq0dXlRTVPL4Nk9ZqRQh FYJlOhM2TGSg7VsNgn8gneODaaQJpJ7jVSIwicQtWES2K2oblrFz4LSeXm39xZDc 0JRNh/fSeRygCGrjD7CLqq88UGTxhEuZbEXKXSPMLC+7j7JF/CmCVj8HjNw8M3Cy uk/Tfamala66AGltxPwKchTPBJH8F4tZy+4krfYXByoIX5h+Ta4= =Fk0g -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAl/q5usACgkQ7ZfpDmKq fjSp4A//aoSQ/VDoYZhE5F7PXV+td9DTVGABdA6ubQppymgX8uJvuBgk46pDRmVw Yba4dVcblTzjbCNDCBf9+nkgj46hGdql10t9bjgBDKf5MVQwp8hDyQfj3qbJciBD E0JSMXw3JQpuK1YVqxTXldINxtaSaLJUhYh1inBmEs8uX+vrwzURmYhF7NLoG7GL ymClE3BAJwkNXuRJ4tAMhEaANdShnre+uJWWW7DeNZPrHVKhSSD7IyAWin3vNUEj FA3ELERWgTVbkpmsUUH+5VtUIp8dE9jGxzgaPfy4KmuN0D4qiEgjSg23AFZDWqwF jDX2OlQl7J9oQfeUUBooee1S6IkVCC0+WNJPhSjeeKV8CUBBT5YKtTAgnx14bgkc nL01dF49WxA2MrQMWd794jh6dpMwDzdWw4gdEMLoiSOKRpO5E5iHzjM7c0WWyrGl Hqh6ZmBZz+17wBFSd7QQtLpwWajl+yGgSONJcw0cnvdjleJ6m89vcdzsrsD55ONT uRZK1TEaZqYG6U6lk/XxDsVQiC1CQ9/vWOPT8bhd2wdIhf9g0skN+MNachKQfs11 9Xn+pfMk79Vgatbbq9rDk0F3v6gRjayYRDtcVCFoOmrdXWmRhQtvyerm6wCILsFU gWpdS8tIo/4dwbypyot/5fe0ZEUBJGfbe7PSZu7a64DTgecE5R8= =mWt8 -----END PGP SIGNATURE----- PS. If your tzdata parser does not yet support negative DST offsets or times past 24:00, or if it insists on a 'pacificnew' file that is no longer present, this release's data entries can be turned into a rearguard-format tarball that should work even with these older parsers. This is intended to be a temporary transition aid for these parsers. To generate a rearguard-format tarball, obtain the full distribution as described above, and run the command 'make rearguard_tarballs' on a development host. Or you can run 'make rearguard.zi' to generate a single file that can be fed directly to a parser that works like 'zic'.

1 0

Joda-Time compiler broken again
by Stephen Colebourne Dec. 28, 2020

Dec. 28, 2020

The latest 2020e release broke the Joda-Time compiler again. https://github.com/JodaOrg/joda-time/runs/1607329443?check_suite_focus=true… Presumably, some rule now contains a 31 in a 30 day month now? Stephen

5 8

[tz-announce] 2020e release of tz code and data available
by Paul Eggert Dec. 27, 2020

Dec. 27, 2020

The 2020e release of the tz code and data is available. It reflects the following changes, which were either circulated on the tz mailing list or are relatively minor technical or administrative changes: Briefly: Volgograd switches to Moscow time on 2020-12-27 at 02:00. Changes to future timestamps Volgograd changes time zone from +04 to +03 on 2020-12-27 at 02:00. (Thanks to Alexander Krivenyshev and Stepan Golosunov.) Changes to past timestamps Correct many pre-1986 transitions, fixing entries originally derived from Shanks. The fixes include: - Australia: several 1917 through 1971 transitions - Bahamas: several 1941 through 1945 transitions - Bermuda: several 1917 through 1956 transitions - Belize: several 1942 through 1968 transitions - Ghana: several 1915 through 1956 transitions - Israel and Palestine: several 1940 through 1985 transitions - Kenya and adjacent: several 1908 through 1960 transitions - Nigeria and adjacent: correcting LMT in Lagos, and several 1905 through 1919 transitions - Seychelles: the introduction of standard time in 1907, not 1906 - Vanuatu: DST in 1973-1974, and a corrected 1984 transition (Thanks to P Chan.) Because of the Australia change, Australia/Currie (King Island) is no longer needed, as it is identical to Australia/Hobart for all timestamps since 1970 and was therefore created by mistake. Australia/Currie has been moved to the 'backward' file and its corrected data moved to the 'backzone' file. Changes to past time zone abbreviations and DST flags To better match legislation in Turks and Caicos, the 2015 shift to year-round observance of -04 is now modeled as AST throughout before returning to Eastern Time with US DST in 2018, rather than as maintaining EDT until 2015-11-01. (Thanks to P Chan.) Changes to documentation The zic man page now documents zic's coalescing of transitions when a zone falls back just before DST springs forward. Here are links to the release files: https://www.iana.org/time-zones/repository/releases/tzcode2020e.tar.gz https://www.iana.org/time-zones/repository/releases/tzdata2020e.tar.gz https://www.iana.org/time-zones/repository/releases/tzdb-2020e.tar.lz As usual, links to the latest release files are here: https://www.iana.org/time-zones/repository/tzcode-latest.tar.gz https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz Links are also available via plain HTTP, and via FTP from ftp://ftp.iana.org/tz/releases with the same basenames as above. Each release file has a GPG signature, which can be retrieved by appending ".asc" to the above URLs. Copies of these signatures are appended to this message. This release corresponds to commit efc5c061920f1d5820d66b7ec88ebff144c55b3f dated 2020-12-22 15:14:34 -0800 and tagged '2020e' in the development GitHub repository at <https://github.com/eggert/tz>. Here are the SHA-512 checksums for the release files: 37656ee4400f6e7ac8b3d4b515ea2ae940de05e8a95873112a4ec08afc11227214f269e4ef1bedb0389497958dd07a6d4721191e441920bc45c235b029a8a885 tzcode2020e.tar.gz 1e64b5c91b9e56923cf8e3e079781c59c8afb6c379b38b9b91ef493929814d50c29a6368cfcf77db08a7af3b6876387bac5617f64ac965a5bddab436d17862c4 tzdata2020e.tar.gz 77e62a3717d179b13f35710dedd87d780649edf6c338c056e41ba58d49225e512074a5fbfa3ae52242bea6b28d1a08bb0e2b07ff7a3aed031dc9d357dac34170 tzdb-2020e.tar.lz Here are the GPG digital signatures for the release files: -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAl/ifpwACgkQ7ZfpDmKq fjQrYA//Z3ky92YK4p8GAejA/69W92B2n+uATB7YPOVJXjWOieo+nmlJihEaY447 bxsLfrExy/AwM5wUoqu9JPQmjUGQYxQR0MjIdpzLeWNCGx+NM8n2j+9K00VXxIXX 356rhSNclm5a/1AmkeeDeYK1C8Fw3QIQnaqeTMHDZ/Txv2UncAMshHR2P+9c2i/k N5A+XK0X3+YNHs/0AHbFobRonynw68cogTeSdslMxFtjWV1iTNNR7c8hHHCDXMgJ sjF7hJ7d6RHBRDQn53XgJdR/OKPaj1RJXncP1Be9j6J1M5wepkHJFVS7/66dDl+g 7TyimxnE/y5gxNVk1JWF9ssz31ksGBRbwq1P8IdF3/EsNF3tTB3eqmKM7PB55Oiu k9MWSDo5/fjfdhH24oYUhocJmMN+n2iiBjAh+mWOq1KNPBGtugbztSZPNXuHDHn9 vsAVuuOdK7FvZcbzE0kMqh3gCmp1YBPcXUSnlqLGaowwlykfoYYR0MGz8AdvJreE 5Su2wfiPlI/B2zvVmJ1i2LFr+9nfVFWlmXGAwFmHunpEKTHB9b0HKXVdsJL9qZC2 Gm7SXPMzHEjZ1G420jT8Bx0qfGLC62jTq98QSK6BdcfLd0AsU+rstmQviFZOtSAv qEPrAXPXUraEwMs2/dR+eXR0DWQMEbUWgtmxJM3jHOGnWRseAQc= =xaDL -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAl/ifpwACgkQ7ZfpDmKq fjSC+w/9HzW/PbI7gfxfbPkF0fCyHCl2OWWrLlJi1m0G72balJ+BmkhI3vvnBGwK 3OKhvN/HOxA4d11JpXiYmPuQ7iuCDO8nRTDWbtg5nuEdP3FOJqUBD0HKDjTg/UUo haXoFxJwPklPqGOiIsFklEQWgVwpN+LwZkL7b2yjjadL0k5ukx6z/G2lJ5qF2i63 f3Gbe/oG/UYd3ERlDpjvgn2tJWfmoS0S3qU3Y9TpraL3NrmunnbtIFDW7SIEM2oP W4XmtkNgBQGlHS1/x/vocNo31h6KyzqVg6OSyvk88Fzp8vE+gHGOVTLR2RdNh/0H NQDi+Pj65KlIJUsjcLmZo+Huv+eNUfzwBcG+LGwUhay0q+2kaeGTs6epohYFNZen A/0/nzXJBohqcBnbLcBYVf+AZUHuPs5lTkG3OZpdRSvkmw6lELlJbBQMEf/HP/kG l43x9DEe0Dr2oDIEr1mfjszFJqKvSg43QJnTgUJtd0SqITazC1N9XuIZj0uXJ64g zfC1aByJ1FLNJmkMDKbl+OzVg7o53sS2gzL/EaGp43NeOPVa84w5MSWdZnuPz8xa 8KDdcaqWeY+mdLonfq5K/DZhOcV6UanBEXFFrmGZymSSqF2zYPpzPBB/7+B29S5F 68v8ScTY8a3fKjhQqrqzNOOKbVMSwM7m8dZ5o69nIW/knvdmxeg= =eekA -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAl/ifp0ACgkQ7ZfpDmKq fjQnxA//ZYROGBW1B1b7EY+j8b8z8oBsrzuN+PHkpmXqXre/rVJfIU7NoRoOoZ27 U3JDYPhQ6jy3fOCkW8Xa/eBwEe9PXfBnlpjAYbQ4d7KUvxzDauNG7Sch/aOKuQqE LIM9B+Gdyojn1dAimKcVh8z+lSH3f+gaL3/kCDAPDCJqxsDpbnzQ5rsgpf7OlkG8 6yBRo4wNsW6D49nEVScCPwtmlMQUBFesV0J49rZ74NL9eArIjjdHgwSSc0RtSTLx VT8yDmV1ZW93W4+ZKwfnyPb/u8w8O5NP42SoWHOdXV40UpyU/jWfioKPhbLr+D1R AU+uPE/GBpIPEd6dL75WNMQWvSPkER+QEcTYdzJIMiqOpwUXEADn5/miH3JiJ1Cx rgkQuukOzmmshL3YiKxWM2WT41NdVZn4MrXx3TfS2gw0Am4zElkRwcNanFc7Ksyl PNoJrypAKPnArG3+P0LSFxq9nQUsaajlYcAqYthRtzTicPA13iXWml/ATh1sw36H rJAEAVBg2TmIHo4/zlEuV7alrnBT0tIz38RtGvGA7lVB0w8ZLrh3BqyezucoK3Zc GsleX8wkJrrWMcdVPnRUCfCosx8IN57349mnL2g5v1B3Ij/ytYy4yDr8H7/vAX2c ddaxW1aluGBzL48ZKKJedDP/vZgRWINXMAyEyqdXW2G33aMsFlw= =IS+h -----END PGP SIGNATURE----- PS. If your tzdata parser does not yet support negative DST offsets or times past 24:00, or if it insists on a 'pacificnew' file that is no longer present, this release's data entries can be turned into a rearguard-format tarball that should work even with these older parsers. This is intended to be a temporary transition aid for these parsers. To generate a rearguard-format tarball, obtain the full distribution as described above, and run the command 'make rearguard_tarballs' on a development host. Or you can run 'make rearguard.zi' to generate a single file that can be fed directly to a parser that works like 'zic'.

4 14

Daylight saving time in Argentina
by Pol Dec. 24, 2020

Dec. 24, 2020

I have some inconsistencies in the database regarding some time changes in Argentina. I would like to know what is the possibility of corroborating and making these changes. To give just one example, 03-06-1993 Buenos Aires, Argentina would still be GMT -2 (due to the time change from -3 to -2 that took place on 10-18-1992) and the return to -2 occurred just the next day (03-07-1993). Thanks in advance Pol Neiman <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> Libre de virus. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

2 1

Time zone and UTC
by Jacques Grillet Dec. 24, 2020

Dec. 24, 2020

Hello Do you propose a database to download ordered by UTC with 2 columns If not, where is it possible to have this data UTC | Time zone name Thank you Meilleures salutations, Jacques Grillet M. 079 219 17 78

2 1

tzdata-latest.tar.gz tarball points to tzdata2020d
by Kiran Ravikumar Dec. 23, 2020

Dec. 23, 2020

Hello, Looks like the latest(tzdata-latest.tar.gz) release tar bundle points to tzdata2020d - https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz. Can we get it updated to tzdata2020e? Thanks, Kiran

2 1

Re: [tz] Volgograd is planning to change its time zone back to Moscow on December 20, 2020
by Paul Eggert Dec. 23, 2020

Dec. 23, 2020

On 12/2/20 2:57 PM, wtz wrote: > (State Duma plan to pass the Bill in the second and third reading next week - > around December 9, 2020) Thanks for keeping us up-to-date. After December 9, it'll still need a look-see by the Federation Council and a signing by the president before it's a done deal. Not much time before the time change on December 20. I suppose people will just use "Europe/Moscow" if their tzdb copies aren't updated in time. Your source says "в скандальном вопросе" ("v skandal'nom voprose"), a curious choice of words. The extreme lack of notice is scandalous from my point of view, and perhaps the source is making the same point.

6 9

[PATCH] Improve doc of zic coalescing zone+DST transitions
by Paul Eggert Dec. 22, 2020

Dec. 22, 2020

* zic.8: Improve documentation for how certain transitions are coalesced. Also, use current data for America/Menominee instead an America/Grand_Turk entry that not in current data. Improvements suggested by Tim Parenti. --- zic.8 | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/zic.8 b/zic.8 index 2273dad..60262d7 100644 --- a/zic.8 +++ b/zic.8 @@ -590,35 +590,41 @@ first transition into standard time. In a single zone it is an error if two rules take effect at the same instant, or if two zone changes take effect at the same instant. .PP -If a continuation line subtracts from the UT offset after a transition that -would be interpreted to be later if using the continuation line's rules, the +If a continuation line subtracts +.I N +seconds from the UT offset after a transition that would be +interpreted to be later if using the continuation line's UT offset and +rules, the .q "until" -time of the earlier zone or continuation line is interpreted according -to the continuation line's rules. +time of the previous zone or continuation line is interpreted +according to the continuation line's UT offset and rules, and any rule +that would otherwise take effect in the next +.I N +seconds is instead assumed to take effect simultaneously. For example: .br .ne 7 .nf .in +2m -.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'max\0\0'u +\w'\*-\0\0'u +\w'Mar\0\0'u +\w'Sun>=8\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u +.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'2006\0\0'u +\w'\*-\0\0'u +\w'Oct\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u .sp # Rule NAME FROM TO \*- IN ON AT SAVE LETTER/S -Rule US 2007 max \*- Mar Sun>=8 2:00 1:00 D -Rule US 2007 max \*- Nov Sun>=1 2:00 0 S -.ta \w'Zone\0\0America/Grand_Turk\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u +Rule US 1967 2006 - Oct lastSun 2:00 0 S +Rule US 1967 1973 - Apr lastSun 2:00 1:00 D +.ta \w'Zone\0\0America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u # Zone\0\0NAME STDOFF RULES FORMAT [UNTIL] -Zone\0\0America/Grand_Turk \*-4:00 \*- AST 2018 Mar 11 2:00 - \*-5:00 US E%sT +Zone\0\0America/Menominee \*-5:00 \*- EST 1973 Apr 29 2:00 + \*-6:00 US C%sT .sp .in .fi -Here, an incorrect reading would be there were two clock changes on 2018-03-11, -the first from 02:00 AST (\*-04) to 01:00 EST (\*-05), -and the second an hour later from 02:00 EST (\*-05) to 03:00 EDT (\*-04). +Here, an incorrect reading would be there were two clock changes on 1973-04-29, +the first from 02:00 EST (\*-05) to 01:00 CST (\*-06), +and the second an hour later from 02:00 CST (\*-06) to 03:00 CDT (\*-05). However, .B zic -interprets this more sensibly as a single transition from 02:00 AST (\*-04) to -02:00 EDT (\*-04). +interprets this more sensibly as a single transition from 02:00 CST (\*-05) to +02:00 CDT (\*-05). .PP A link line has the form .sp -- 2.27.0

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