unix - 时区数据库文件格式问题

Question

我正在从 Olson 数据库生成的时区文件中读取时区更改的时间以及它们更改的内容。时区文件的格式在 tzfile.h 中描述。

对于我的问题，我将使用我获得的欧洲/罗马数据。

我可能让它正常工作，因为我的输出与 timeanddate.com 所说的正确匹配。例如，我的程序正确地说:

On March 28, 1982 02:00:00 the timezone changes to GMT +2.000000.

On September 26, 1982 03:00:00 the timezone changes to GMT +1.000000.

这在此处得到证实:
http://www.timeanddate.com/worldclock/clockchange.html?n=215&year=1982

但是，我不确定是否需要使用 tzh_ttisstdcnt 和 tzh_ttisgmtcnt。

从 tzfile.h:

Then there are tzh_ttisstdcnt standard/wall indicators, each stored as a one-byte value; they tell whether the transition times associated with local time types were specified as standard time or wall clock time, and are used when a timezone file is used in handling POSIX-style timezone environment variables.

Finally, there are tzh_ttisgmtcnt UTC/local indicators, each stored as a one-byte value; they tell whether the transition times associated with local time types were specified as UTC or local time, and are used when a timezone file is used in handling POSIX-style timezone environment variables.

我发现每个“时间类型”(ttinfo 结构)都有一个 isstd 和 isgmt 字节。
这些是欧洲/罗马的 6 种“时间类型”:

 Type 0, CEST, DST? = 1, GMT+2, isstd? = 1, isgmt? = 0
 Type 1, CET,  DST? = 0, GMT+1, isstd? = 1, isgmt? = 0
 Type 2, CEST, DST? = 1, GMT+2, isstd? = 0, isgmt? = 0
 Type 3, CET,  DST? = 0, GMT+1, isstd? = 0, isgmt? = 0
 Type 4, CEST, DST? = 1, GMT+2, isstd? = 1, isgmt? = 1
 Type 5, CET,  DST? = 0, GMT+1, isstd? = 1, isgmt? = 1

tzfile.h 听起来像 isstd 和 isgmt 告诉你转换时间是如何存储的(gmt vs localtime)。但是，我的代码目前假定所有转换时间都存储为 GMT。我的程序的输出与所有 6 种转换类型的 timeanddate.com 匹配。

另外，我不明白 0 和 1 类型如何可以是 std 而不是 gmt。我以为格林威治标准时间是标准时间。

任何解释都会很棒。

编辑:

当我忽略 isstd 和 isgmt 选项时，我的输出似乎与 timeanddate.com 上的数据几乎匹配。我目前将所有过渡时间解释为 GMT:

罗马的过渡类型:

new type 0: isdst = 1 offset = 7200 abbreviation = 0 isstd = 1 isgmt = 0

new type 1: isdst = 0 offset = 3600 abbreviation = 5 isstd = 1 isgmt = 0

new type 2: isdst = 1 offset = 7200 abbreviation = 0 isstd = 0 isgmt = 0

new type 3: isdst = 0 offset = 3600 abbreviation = 5 isstd = 0 isgmt = 0

new type 4: isdst = 1 offset = 7200 abbreviation = 0 isstd = 1 isgmt = 1

罗马的数据(假设所有过渡时间均以格林威治标准时间给出):

The starting timezone is GMT+1
type: 0, transition time in file:-1690851600
Add previous offset to get transition as (localtime): June 03, 1916 00:00:00 GMT+2

**type: 1, transition time in file:-1680483600
Add previous offset to get transition as (localtime): October 01, 1916 01:00:00 GMT+1**

type: 0, transition time in file:-1664758800
Add previous offset to get transition as (localtime): April 01, 1917 00:00:00 GMT+2

type: 1, transition time in file:-1649034000
Add previous offset to get transition as (localtime): September 30, 1917 01:00:00 GMT+1

type: 0, transition time in file:-1635123600
Add previous offset to get transition as (localtime): March 10, 1918 00:00:00 GMT+2

type: 1, transition time in file:-1616979600
Add previous offset to get transition as (localtime): October 06, 1918 01:00:00 GMT+1

type: 0, transition time in file:-1604278800
Add previous offset to get transition as (localtime): March 02, 1919 00:00:00 GMT+2

type: 1, transition time in file:-1585530000
Add previous offset to get transition as (localtime): October 05, 1919 01:00:00 GMT+1

type: 0, transition time in file:-1571014800
Add previous offset to get transition as (localtime): March 21, 1920 00:00:00 GMT+2

type: 1, transition time in file:-1555290000
Add previous offset to get transition as (localtime): September 19, 1920 01:00:00 GMT+1

type: 0, transition time in file:-932432400
Add previous offset to get transition as (localtime): June 15, 1940 00:00:00 GMT+2

type: 1, transition time in file:-857257200
Add previous offset to get transition as (localtime): November 02, 1942 03:00:00 GMT+1

type: 0, transition time in file:-844556400
Add previous offset to get transition as (localtime): March 29, 1943 02:00:00 GMT+2

type: 1, transition time in file:-828226800
Add previous offset to get transition as (localtime): October 04, 1943 03:00:00 GMT+1

type: 0, transition time in file:-812502000
Add previous offset to get transition as (localtime): April 03, 1944 02:00:00 GMT+2

type: 1, transition time in file:-798080400
Add previous offset to get transition as (localtime): September 17, 1944 01:00:00 GMT+1

type: 2, transition time in file:-781052400
Add previous offset to get transition as (localtime): April 02, 1945 02:00:00 GMT+2

type: 1, transition time in file:-766717200
Add previous offset to get transition as (localtime): September 15, 1945 01:00:00 GMT+1

type: 0, transition time in file:-750898800
Add previous offset to get transition as (localtime): March 17, 1946 02:00:00 GMT+2

type: 1, transition time in file:-733359600
Add previous offset to get transition as (localtime): October 06, 1946 03:00:00 GMT+1

type: 0, transition time in file:-719456400
Add previous offset to get transition as (localtime): March 16, 1947 00:00:00 GMT+2

type: 1, transition time in file:-701917200
Add previous offset to get transition as (localtime): October 05, 1947 01:00:00 GMT+1

type: 0, transition time in file:-689209200
Add previous offset to get transition as (localtime): February 29, 1948 02:00:00 GMT+2

type: 1, transition time in file:-670460400
Add previous offset to get transition as (localtime): October 03, 1948 03:00:00 GMT+1

type: 2, transition time in file:-114051600
Add previous offset to get transition as (localtime): May 22, 1966 00:00:00 GMT+2

type: 3, transition time in file:-103168800
Add previous offset to get transition as (localtime): September 25, 1966 00:00:00 GMT+1

type: 2, transition time in file:-81997200
Add previous offset to get transition as (localtime): May 28, 1967 00:00:00 GMT+2

type: 3, transition time in file:-71719200
Add previous offset to get transition as (localtime): September 24, 1967 00:00:00 GMT+1

type: 2, transition time in file:-50547600
Add previous offset to get transition as (localtime): May 26, 1968 00:00:00 GMT+2

type: 3, transition time in file:-40269600
Add previous offset to get transition as (localtime): September 22, 1968 00:00:00 GMT+1

type: 2, transition time in file:-18493200
Add previous offset to get transition as (localtime): June 01, 1969 00:00:00 GMT+2

type: 3, transition time in file:-8215200
Add previous offset to get transition as (localtime): September 28, 1969 00:00:00 GMT+1

type: 2, transition time in file:12956400
Add previous offset to get transition as (localtime): May 31, 1970 00:00:00 GMT+2

type: 3, transition time in file:23234400
Add previous offset to get transition as (localtime): September 27, 1970 00:00:00 GMT+1

type: 2, transition time in file:43801200
Add previous offset to get transition as (localtime): May 23, 1971 00:00:00 GMT+2

type: 3, transition time in file:54687600
Add previous offset to get transition as (localtime): September 26, 1971 01:00:00 GMT+1

type: 2, transition time in file:75855600
Add previous offset to get transition as (localtime): May 28, 1972 00:00:00 GMT+2

type: 3, transition time in file:86738400
Add previous offset to get transition as (localtime): October 01, 1972 00:00:00 GMT+1

type: 2, transition time in file:107910000
Add previous offset to get transition as (localtime): June 03, 1973 00:00:00 GMT+2

type: 3, transition time in file:118188000
Add previous offset to get transition as (localtime): September 30, 1973 00:00:00 GMT+1

type: 2, transition time in file:138754800
Add previous offset to get transition as (localtime): May 26, 1974 00:00:00 GMT+2

type: 3, transition time in file:149637600
Add previous offset to get transition as (localtime): September 29, 1974 00:00:00 GMT+1

type: 0, transition time in file:170809200
Add previous offset to get transition as (localtime): June 01, 1975 00:00:00 GMT+2

type: 1, transition time in file:181090800
Add previous offset to get transition as (localtime): September 28, 1975 01:00:00 GMT+1

type: 0, transition time in file:202258800
Add previous offset to get transition as (localtime): May 30, 1976 00:00:00 GMT+2

type: 1, transition time in file:212540400
Add previous offset to get transition as (localtime): September 26, 1976 01:00:00 GMT+1

type: 0, transition time in file:233103600
Add previous offset to get transition as (localtime): May 22, 1977 00:00:00 GMT+2

type: 1, transition time in file:243990000
Add previous offset to get transition as (localtime): September 25, 1977 01:00:00 GMT+1

type: 0, transition time in file:265158000
Add previous offset to get transition as (localtime): May 28, 1978 00:00:00 GMT+2

type: 1, transition time in file:276044400
Add previous offset to get transition as (localtime): October 01, 1978 01:00:00 GMT+1

type: 0, transition time in file:296607600
Add previous offset to get transition as (localtime): May 27, 1979 00:00:00 GMT+2

type: 1, transition time in file:307494000
Add previous offset to get transition as (localtime): September 30, 1979 01:00:00 GMT+1

type: 4, transition time in file:323830800
Add previous offset to get transition as (localtime): April 06, 1980 02:00:00 GMT+2

type: 5, transition time in file:338950800
Add previous offset to get transition as (localtime): September 28, 1980 03:00:00 GMT+1

type: 4, transition time in file:354675600
Add previous offset to get transition as (localtime): March 29, 1981 02:00:00 GMT+2

type: 5, transition time in file:370400400
Add previous offset to get transition as (localtime): September 27, 1981 03:00:00 GMT+1

type: 4, transition time in file:386125200
Add previous offset to get transition as (localtime): March 28, 1982 02:00:00 GMT+2

type: 5, transition time in file:401850000
Add previous offset to get transition as (localtime): September 26, 1982 03:00:00 GMT+1

type: 4, transition time in file:417574800
Add previous offset to get transition as (localtime): March 27, 1983 02:00:00 GMT+2

type: 5, transition time in file:433299600
Add previous offset to get transition as (localtime): September 25, 1983 03:00:00 GMT+1

type: 4, transition time in file:449024400
Add previous offset to get transition as (localtime): March 25, 1984 02:00:00 GMT+2

type: 5, transition time in file:465354000
Add previous offset to get transition as (localtime): September 30, 1984 03:00:00 GMT+1

type: 4, transition time in file:481078800
Add previous offset to get transition as (localtime): March 31, 1985 02:00:00 GMT+2

type: 5, transition time in file:496803600
Add previous offset to get transition as (localtime): September 29, 1985 03:00:00 GMT+1

type: 4, transition time in file:512528400
Add previous offset to get transition as (localtime): March 30, 1986 02:00:00 GMT+2

type: 5, transition time in file:528253200
Add previous offset to get transition as (localtime): September 28, 1986 03:00:00 GMT+1

type: 4, transition time in file:543978000
Add previous offset to get transition as (localtime): March 29, 1987 02:00:00 GMT+2

type: 5, transition time in file:559702800
Add previous offset to get transition as (localtime): September 27, 1987 03:00:00 GMT+1

type: 4, transition time in file:575427600
Add previous offset to get transition as (localtime): March 27, 1988 02:00:00 GMT+2

type: 5, transition time in file:591152400
Add previous offset to get transition as (localtime): September 25, 1988 03:00:00 GMT+1

type: 4, transition time in file:606877200
Add previous offset to get transition as (localtime): March 26, 1989 02:00:00 GMT+2

type: 5, transition time in file:622602000
Add previous offset to get transition as (localtime): September 24, 1989 03:00:00 GMT+1

type: 4, transition time in file:638326800
Add previous offset to get transition as (localtime): March 25, 1990 02:00:00 GMT+2

type: 5, transition time in file:654656400
Add previous offset to get transition as (localtime): September 30, 1990 03:00:00 GMT+1

type: 4, transition time in file:670381200
Add previous offset to get transition as (localtime): March 31, 1991 02:00:00 GMT+2

type: 5, transition time in file:686106000
Add previous offset to get transition as (localtime): September 29, 1991 03:00:00 GMT+1

type: 4, transition time in file:701830800
Add previous offset to get transition as (localtime): March 29, 1992 02:00:00 GMT+2

type: 5, transition time in file:717555600
Add previous offset to get transition as (localtime): September 27, 1992 03:00:00 GMT+1

type: 4, transition time in file:733280400
Add previous offset to get transition as (localtime): March 28, 1993 02:00:00 GMT+2

type: 5, transition time in file:749005200
Add previous offset to get transition as (localtime): September 26, 1993 03:00:00 GMT+1

type: 4, transition time in file:764730000
Add previous offset to get transition as (localtime): March 27, 1994 02:00:00 GMT+2

type: 5, transition time in file:780454800
Add previous offset to get transition as (localtime): September 25, 1994 03:00:00 GMT+1

type: 4, transition time in file:796179600
Add previous offset to get transition as (localtime): March 26, 1995 02:00:00 GMT+2

type: 5, transition time in file:811904400
Add previous offset to get transition as (localtime): September 24, 1995 03:00:00 GMT+1

type: 4, transition time in file:828234000
Add previous offset to get transition as (localtime): March 31, 1996 02:00:00 GMT+2

type: 5, transition time in file:846378000
Add previous offset to get transition as (localtime): October 27, 1996 03:00:00 GMT+1

type: 4, transition time in file:859683600
Add previous offset to get transition as (localtime): March 30, 1997 02:00:00 GMT+2

type: 5, transition time in file:877827600
Add previous offset to get transition as (localtime): October 26, 1997 03:00:00 GMT+1

type: 4, transition time in file:891133200
Add previous offset to get transition as (localtime): March 29, 1998 02:00:00 GMT+2

type: 5, transition time in file:909277200
Add previous offset to get transition as (localtime): October 25, 1998 03:00:00 GMT+1

type: 4, transition time in file:922582800
Add previous offset to get transition as (localtime): March 28, 1999 02:00:00 GMT+2

type: 5, transition time in file:941331600
Add previous offset to get transition as (localtime): October 31, 1999 03:00:00 GMT+1

type: 4, transition time in file:954032400
Add previous offset to get transition as (localtime): March 26, 2000 02:00:00 GMT+2

type: 5, transition time in file:972781200
Add previous offset to get transition as (localtime): October 29, 2000 03:00:00 GMT+1

type: 4, transition time in file:985482000
Add previous offset to get transition as (localtime): March 25, 2001 02:00:00 GMT+2

type: 5, transition time in file:1004230800
Add previous offset to get transition as (localtime): October 28, 2001 03:00:00 GMT+1

type: 4, transition time in file:1017536400
Add previous offset to get transition as (localtime): March 31, 2002 02:00:00 GMT+2

type: 5, transition time in file:1035680400
Add previous offset to get transition as (localtime): October 27, 2002 03:00:00 GMT+1

type: 4, transition time in file:1048986000
Add previous offset to get transition as (localtime): March 30, 2003 02:00:00 GMT+2

type: 5, transition time in file:1067130000
Add previous offset to get transition as (localtime): October 26, 2003 03:00:00 GMT+1

type: 4, transition time in file:1080435600
Add previous offset to get transition as (localtime): March 28, 2004 02:00:00 GMT+2

type: 5, transition time in file:1099184400
Add previous offset to get transition as (localtime): October 31, 2004 03:00:00 GMT+1

type: 4, transition time in file:1111885200
Add previous offset to get transition as (localtime): March 27, 2005 02:00:00 GMT+2

type: 5, transition time in file:1130634000
Add previous offset to get transition as (localtime): October 30, 2005 03:00:00 GMT+1

type: 4, transition time in file:1143334800
Add previous offset to get transition as (localtime): March 26, 2006 02:00:00 GMT+2

type: 5, transition time in file:1162083600
Add previous offset to get transition as (localtime): October 29, 2006 03:00:00 GMT+1

type: 4, transition time in file:1174784400
Add previous offset to get transition as (localtime): March 25, 2007 02:00:00 GMT+2

type: 5, transition time in file:1193533200
Add previous offset to get transition as (localtime): October 28, 2007 03:00:00 GMT+1

type: 4, transition time in file:1206838800
Add previous offset to get transition as (localtime): March 30, 2008 02:00:00 GMT+2

type: 5, transition time in file:1224982800
Add previous offset to get transition as (localtime): October 26, 2008 03:00:00 GMT+1

type: 4, transition time in file:1238288400
Add previous offset to get transition as (localtime): March 29, 2009 02:00:00 GMT+2

type: 5, transition time in file:1256432400
Add previous offset to get transition as (localtime): October 25, 2009 03:00:00 GMT+1

type: 4, transition time in file:1269738000
Add previous offset to get transition as (localtime): March 28, 2010 02:00:00 GMT+2

type: 5, transition time in file:1288486800
Add previous offset to get transition as (localtime): October 31, 2010 03:00:00 GMT+1

type: 4, transition time in file:1301187600
Add previous offset to get transition as (localtime): March 27, 2011 02:00:00 GMT+2

type: 5, transition time in file:1319936400
Add previous offset to get transition as (localtime): October 30, 2011 03:00:00 GMT+1

type: 4, transition time in file:1332637200
Add previous offset to get transition as (localtime): March 25, 2012 02:00:00 GMT+2

type: 5, transition time in file:1351386000
Add previous offset to get transition as (localtime): October 28, 2012 03:00:00 GMT+1

type: 4, transition time in file:1364691600
Add previous offset to get transition as (localtime): March 31, 2013 02:00:00 GMT+2

type: 5, transition time in file:1382835600
Add previous offset to get transition as (localtime): October 27, 2013 03:00:00 GMT+1

type: 4, transition time in file:1396141200
Add previous offset to get transition as (localtime): March 30, 2014 02:00:00 GMT+2

type: 5, transition time in file:1414285200
Add previous offset to get transition as (localtime): October 26, 2014 03:00:00 GMT+1

type: 4, transition time in file:1427590800
Add previous offset to get transition as (localtime): March 29, 2015 02:00:00 GMT+2

type: 5, transition time in file:1445734800
Add previous offset to get transition as (localtime): October 25, 2015 03:00:00 GMT+1

type: 4, transition time in file:1459040400
Add previous offset to get transition as (localtime): March 27, 2016 02:00:00 GMT+2

type: 5, transition time in file:1477789200
Add previous offset to get transition as (localtime): October 30, 2016 03:00:00 GMT+1

type: 4, transition time in file:1490490000
Add previous offset to get transition as (localtime): March 26, 2017 02:00:00 GMT+2

type: 5, transition time in file:1509238800
Add previous offset to get transition as (localtime): October 29, 2017 03:00:00 GMT+1

type: 4, transition time in file:1521939600
Add previous offset to get transition as (localtime): March 25, 2018 02:00:00 GMT+2

type: 5, transition time in file:1540688400
Add previous offset to get transition as (localtime): October 28, 2018 03:00:00 GMT+1

type: 4, transition time in file:1553994000
Add previous offset to get transition as (localtime): March 31, 2019 02:00:00 GMT+2

type: 5, transition time in file:1572138000
Add previous offset to get transition as (localtime): October 27, 2019 03:00:00 GMT+1

type: 4, transition time in file:1585443600
Add previous offset to get transition as (localtime): March 29, 2020 02:00:00 GMT+2

type: 5, transition time in file:1603587600
Add previous offset to get transition as (localtime): October 25, 2020 03:00:00 GMT+1

type: 4, transition time in file:1616893200
Add previous offset to get transition as (localtime): March 28, 2021 02:00:00 GMT+2

type: 5, transition time in file:1635642000
Add previous offset to get transition as (localtime): October 31, 2021 03:00:00 GMT+1

type: 4, transition time in file:1648342800
Add previous offset to get transition as (localtime): March 27, 2022 02:00:00 GMT+2

type: 5, transition time in file:1667091600
Add previous offset to get transition as (localtime): October 30, 2022 03:00:00 GMT+1

type: 4, transition time in file:1679792400
Add previous offset to get transition as (localtime): March 26, 2023 02:00:00 GMT+2

type: 5, transition time in file:1698541200
Add previous offset to get transition as (localtime): October 29, 2023 03:00:00 GMT+1

type: 4, transition time in file:1711846800
Add previous offset to get transition as (localtime): March 31, 2024 02:00:00 GMT+2

type: 5, transition time in file:1729990800
Add previous offset to get transition as (localtime): October 27, 2024 03:00:00 GMT+1

type: 4, transition time in file:1743296400
Add previous offset to get transition as (localtime): March 30, 2025 02:00:00 GMT+2

type: 5, transition time in file:1761440400
Add previous offset to get transition as (localtime): October 26, 2025 03:00:00 GMT+1

type: 4, transition time in file:1774746000
Add previous offset to get transition as (localtime): March 29, 2026 02:00:00 GMT+2

type: 5, transition time in file:1792890000
Add previous offset to get transition as (localtime): October 25, 2026 03:00:00 GMT+1

type: 4, transition time in file:1806195600
Add previous offset to get transition as (localtime): March 28, 2027 02:00:00 GMT+2

type: 5, transition time in file:1824944400
Add previous offset to get transition as (localtime): October 31, 2027 03:00:00 GMT+1

type: 4, transition time in file:1837645200
Add previous offset to get transition as (localtime): March 26, 2028 02:00:00 GMT+2

type: 5, transition time in file:1856394000
Add previous offset to get transition as (localtime): October 29, 2028 03:00:00 GMT+1

type: 4, transition time in file:1869094800
Add previous offset to get transition as (localtime): March 25, 2029 02:00:00 GMT+2

type: 5, transition time in file:1887843600
Add previous offset to get transition as (localtime): October 28, 2029 03:00:00 GMT+1

type: 4, transition time in file:1901149200
Add previous offset to get transition as (localtime): March 31, 2030 02:00:00 GMT+2

type: 5, transition time in file:1919293200
Add previous offset to get transition as (localtime): October 27, 2030 03:00:00 GMT+1

type: 4, transition time in file:1932598800
Add previous offset to get transition as (localtime): March 30, 2031 02:00:00 GMT+2

type: 5, transition time in file:1950742800
Add previous offset to get transition as (localtime): October 26, 2031 03:00:00 GMT+1

type: 4, transition time in file:1964048400
Add previous offset to get transition as (localtime): March 28, 2032 02:00:00 GMT+2

type: 5, transition time in file:1982797200
Add previous offset to get transition as (localtime): October 31, 2032 03:00:00 GMT+1

type: 4, transition time in file:1995498000
Add previous offset to get transition as (localtime): March 27, 2033 02:00:00 GMT+2

type: 5, transition time in file:2014246800
Add previous offset to get transition as (localtime): October 30, 2033 03:00:00 GMT+1

type: 4, transition time in file:2026947600
Add previous offset to get transition as (localtime): March 26, 2034 02:00:00 GMT+2

type: 5, transition time in file:2045696400
Add previous offset to get transition as (localtime): October 29, 2034 03:00:00 GMT+1

type: 4, transition time in file:2058397200
Add previous offset to get transition as (localtime): March 25, 2035 02:00:00 GMT+2

type: 5, transition time in file:2077146000
Add previous offset to get transition as (localtime): October 28, 2035 03:00:00 GMT+1

type: 4, transition time in file:2090451600
Add previous offset to get transition as (localtime): March 30, 2036 02:00:00 GMT+2

type: 5, transition time in file:2108595600
Add previous offset to get transition as (localtime): October 26, 2036 03:00:00 GMT+1

type: 4, transition time in file:2121901200
Add previous offset to get transition as (localtime): March 29, 2037 02:00:00 GMT+2

type: 5, transition time in file:2140045200
Add previous offset to get transition as (localtime): October 25, 2037 03:00:00 GMT+1

我的第 2 次和第 4 次转换比列出的 here 晚一个小时，但几乎所有其他内容看起来都匹配。

Answer 1

“标准时间”指的是“冬令时”，而不是“夏令时”或“夏令时”。是的，GMT(松散地；严格地，UTC)是“时间标准”，但它与数据中“isstd”列所指的内容并不完全相同。

'isstd' 为 0 或 1 的要点是欧洲的过渡时间(通常)指定为在当前时区的 02:00 发生。

因此，欧洲/罗马的时钟变为:

1982-03-28 01:59:59 (UTC+01:00)
1982-03-28 03:00:00 (UTC+02:00)

这种转换被记录为在 02:00 标准时间发生(所以 isstd = 1)，但这不是 UTC (GMT) 时间；因此它是您列表中的 0 型转换。相反，在秋天，时钟走了:

1982-09-26 01:59:59 (UTC+02:00)
1982-09-26 01:00:00 (UTC+01:00)

据记录，转换发生在转换之前的时区的 02:00，因此 isstd = 0 (但它不是 UTC (GMT) 时间)；因此，这是您列表中的第 3 类转换。

其他组合(类型 1、2、4、5)出现在其他情况下。对于相同的两个转换，您将使用类型 4 条目并将更改时间记录为 01:00 UTC(因为 01:00:00+00:00 与 02:00:00+01:00 相同；并且您将使用类型 5 条目并将更改时间记录为 00:00 UTC(因为 00:00:00+00:00 与 02:00:00+02:00 相同)。注意这里的切换时间彼此不同。描述中的类似差异适用于类型 1 和类型 2。