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author | Paul Eggert <eggert@cs.ucla.edu> | 2019-05-16 15:23:37 -0700 |
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committer | Paul Eggert <eggert@cs.ucla.edu> | 2019-05-16 15:23:37 -0700 |
commit | 3ff2958b7d4ea2ea0ffcd6514ffdd8296d7a5f4f (patch) | |
tree | c068d5c22123a74598ac9b918955a99fc5e06563 /zic.8 | |
parent | fcba22a8df435a43a98eb25e8ec902340af0f0ed (diff) | |
download | tz-3ff2958b7d4ea2ea0ffcd6514ffdd8296d7a5f4f.tar.gz |
Bring zic man page up to date
* zic.8: Don’t mention time(2), since zic does not rely on time_t
any more. Mention other ways that -v generates warnings.
ON fields can’t contain non-space white space characters either.
Remove incorrect assertion that fractional seconds are not allowed.
Diffstat (limited to 'zic.8')
-rw-r--r-- | zic.8 | 60 |
1 files changed, 48 insertions, 12 deletions
@@ -110,9 +110,7 @@ Be more verbose, and complain about the following situations: The input specifies a link to a link. .PP A year that appears in a data file is outside the range -of years representable by -.BR time (2) -values. +of representable years. .PP A time of 24:00 or more appears in the input. Pre-1998 versions of @@ -124,6 +122,36 @@ Pre-2004 versions of .B zic prohibit this. .PP +A time zone abbreviation uses a +.B %z +format. +Pre-2015 versions of +.B zic +do not support this. +.PP +A timestamp contains fractional seconds. +Pre-2018 versions of +.B zic +do not support this. +.PP +The input contains abbreviations that are mishandled by pre-2018 versions of +.B zic +due to a longstanding coding bug. +These abbreviations include +.q L +for +.q Link , +.q mi +for +.q min , +.q Sa +for +.q Sat , +and +.q Su +for +.q Sun . +.PP The output file does not contain all the information about the long-term future of a timezone, because the future cannot be summarized as an extended POSIX TZ string. For example, as of 2019 this problem @@ -137,8 +165,15 @@ code designed for older output formats. These compatibility issues affect only timestamps before 1970 or after the start of 2038. .PP -A time zone abbreviation has fewer than 3 characters. -POSIX requires at least 3. +The output file contains more than 1200 transitions, +which may be mishandled by some clients. +The current reference client supports at most 2000 transitions; +pre-2014 versions of the reference client support at most 1200 +transitions. +.PP +A time zone abbreviation has fewer than 3 or more than 6 characters. +POSIX requires at least 3, and requires implementations to support +at least 6. .PP An output file name contains a byte that is not an ASCII letter, .q "\*-" , @@ -279,7 +314,7 @@ or a weekday name preceded by (e.g., .BR "lastSunday" ) may be abbreviated or spelled out in full. -Note that there must be no spaces within the +There must be no white space characters within the .B ON field. .TP @@ -455,7 +490,7 @@ and .TP .B UNTIL The time at which the UT offset or the rule(s) change for a location. -It takes the form of YEAR [MONTH [DAY [TIME]]]. +It takes the form of one to four fields YEAR [MONTH [DAY [TIME]]]. If this is specified, the time zone information is generated from the given UT offset and rule change until the time specified, which is interpreted using @@ -587,10 +622,10 @@ Rule EU 1979 1995 \*- Sep lastSun 1:00u 0 \*- Rule EU 1981 max \*- Mar lastSun 1:00u 1:00 S Rule EU 1996 max \*- Oct lastSun 1:00u 0 \*- .sp -.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:34:08\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u +.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:29:45.50\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u # Zone NAME UTOFF RULES FORMAT [UNTIL] Zone Europe/Zurich 0:34:08 \*- LMT 1853 Jul 16 - 0:29:46 \*- BMT 1894 Jun + 0:29:45.50 \*- BMT 1894 Jun 1:00 Swiss CE%sT 1981 1:00 EU CE%sT .sp @@ -601,9 +636,10 @@ Link Europe/Zurich Europe/Vaduz In this example, the timezone is named Europe/Zurich but it has an alias as Europe/Vaduz. This example says that Zurich was 34 minutes and 8 seconds east of UT until 1853-07-16 at 00:00, when the legal offset -was changed to 7\(de\|26\(fm\|22.50\(sd; although this works out to -0:29:45.50, the input format cannot represent fractional seconds so it -is rounded here. After 1894-06-01 at 00:00 the UT offset became one hour +was changed to 7\(de\|26\(fm\|22.50\(sd, which works out to 0:29:45.50; +.B zic +treats this by rounding it to 0:29:46. +After 1894-06-01 at 00:00 the UT offset became one hour and Swiss daylight saving rules (defined with lines beginning with .q "Rule Swiss") apply. From 1981 to the present, EU daylight saving rules have |