From 5336cb27ab42f27b8b8ac31982e8215fe5af6f34 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Wed, 13 Jul 2022 18:54:56 -0700 Subject: [PATCH] * doc/parse-datetime.texi: Tweak wording again. --- doc/parse-datetime.texi | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/doc/parse-datetime.texi b/doc/parse-datetime.texi index 7939273691..e1ce97220a 100644 --- a/doc/parse-datetime.texi +++ b/doc/parse-datetime.texi @@ -551,31 +551,34 @@ location name in a @env{TZ} setting, e.g., @samp{TZ=":America/New_York"}. The @samp{tz} database includes a wide variety of locations ranging -from @samp{Arctic/Longyearbyen} to @samp{Antarctica/South_Pole}, but +from @samp{Africa/Abidjan} to @samp{Pacific/Tongatapu}, but if you are at sea and have your own private time zone, or if you are using a non-GNU host that does not support the @samp{tz} database, you may need to use a POSIX rule instead. The previously-mentioned POSIX rule @samp{UTC0} says that the time zone abbreviation is @samp{UTC}, the zone is zero hours away from Greenwich, and there is no daylight saving time. -Simple POSIX rules like this can also specify nonzero Greenwich offsets. +POSIX rules can also specify nonzero Greenwich offsets. For example, the following shell transcript answers the question ``What time is it five and a half hours east of Greenwich when a clock seven hours west of Greenwich shows 9:50pm on July 12, 2022?'' @example -$ TZ="<+0530>-5:30" date --date='TZ="<-07>7" 2022-07-12 21:50' +$ TZ="<+0530>-5:30" date --date='TZ="<-07>+7" 2022-07-12 21:50' Wed Jul 13 10:20:00 +0530 2022 @end example @noindent -This example uses the somewhat-confusing POSIX convention for TZ strings. -@samp{TZ="<-07>7"} says that the time zone abbreviation is @samp{-07} +This example uses the somewhat-confusing POSIX convention for rules. +@samp{TZ="<-07>+7"} says that the time zone abbreviation is @samp{-07} and the time zone is 7 hours west of Greenwich, and @samp{TZ="<+0530>-5:30"} says that the time zone abbreviation is @samp{+0530} and the time zone is 5 hours 30 minutes east of Greenwich. -More-complex POSIX TZ strings can specify simple daylight saving -regimes. @xref{TZ Variable,, Specifying the Time Zone with @code{TZ}, +Although trickier POSIX @env{TZ} settings like +@samp{TZ="<-05>+5<-04>,M3.2.0/2,M11.1.0/2"} can specify some daylight +saving regimes, location-based settings like +@samp{TZ="America/New_York"} are typically simpler and more accurate +historically. @xref{TZ Variable,, Specifying the Time Zone with @code{TZ}, libc, The GNU C Library}. @node Authors of parse_datetime -- 2.34.1