From: Paul Eggert Date: Fri, 30 Dec 2022 03:16:09 +0000 (-0800) Subject: Document calc-time-zone abbreviation obsolescence X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=523261b454058d0b28df2c3de1eab55fe378aa69;p=emacs.git Document calc-time-zone abbreviation obsolescence * doc/misc/calc.texi (Time Zones): Document that alphabetic time zone abbreviations are obsolescent and in some cases wrong. --- diff --git a/doc/misc/calc.texi b/doc/misc/calc.texi index ef9990c057a..e5bac25cac8 100644 --- a/doc/misc/calc.texi +++ b/doc/misc/calc.texi @@ -17341,8 +17341,12 @@ it can be a variable which is a time zone name in upper- or lower-case. For example @samp{tzone(PST) = tzone(8)} and @samp{tzone(pdt) = tzone(7)} (for Pacific standard and daylight saving times, respectively). -North American and European time zone names are defined as follows; -note that for each time zone there is one name for standard time, +North American and European time zone names are defined as follows. +These names are obsolescent and new code should not rely on them: +the @samp{YST}-related names have disagreed with time in Yukon since 1973, +and other names could well become confusing or wrong in the future +as countries change their time zone rules. +For each time zone there is one name for standard time, another for daylight saving time, and a third for ``generalized'' time in which the daylight saving adjustment is computed from context. @@ -17364,7 +17368,7 @@ To define time zone names that do not appear in the above table, you must modify the Lisp variable @code{math-tzone-names}. This is a list of lists describing the different time zone names; its structure is best explained by an example. The three entries for -Pacific Time look like this: +circa-2022 US Pacific Time look like this: @smallexample @group