diff options
Diffstat (limited to 'lib/libc/time/Theory')
| -rw-r--r-- | lib/libc/time/Theory | 50 |
1 files changed, 37 insertions, 13 deletions
diff --git a/lib/libc/time/Theory b/lib/libc/time/Theory index 438845f2538..771ad484cff 100644 --- a/lib/libc/time/Theory +++ b/lib/libc/time/Theory @@ -1,4 +1,5 @@ -@(#)Theory 7.12 +$OpenBSD: Theory,v 1.8 2002/04/04 19:12:09 millert Exp $ +@(#)Theory 7.13 ----- Outline ----- @@ -35,7 +36,7 @@ POSIX.1 has the following properties and limitations. stdoffset[dst[offset],date[/time],date[/time]] where: - + std and dst are 3 or more characters specifying the standard and daylight saving time (DST) zone names. @@ -179,11 +180,34 @@ so much the better. ----- Names of time zone rule files ----- -The names of this package's installed time zone rule files are chosen to -help minimize possible future incompatibilities due to political events. -Ordinarily, names of countries are not used, to avoid incompatibilities -when countries change their name (e.g. Zaire->Congo) or -when locations change countries (e.g. Hong Kong from UK colony to China). +The time zone rule file naming conventions attempt to strike a balance +among the following goals: + + * Uniquely identify every national region where clocks have all + agreed since 1970. This is essential for the intended use: static + clocks keeping local civil time. + + * Indicate to humans as to where that region is. This simplifes use. + + * Be robust in the presence of political changes. This reduces the + number of updates and backward-compatibility hacks. For example, + names of countries are ordinarily not used, to avoid + incompatibilities when countries change their name + (e.g. Zaire->Congo) or when locations change countries + (e.g. Hong Kong from UK colony to China). + + * Be portable to a wide variety of implementations. + This promotes use of the technology. + + * Use a consistent naming convention over the entire world. + This simplifies both use and maintenance. + +This naming convention is not intended for use by inexperienced users +to select TZ values by themselves (though they can of course examine +and reuse existing settings). Distributors should provide +documentation and/or a simple selection interface that explains the +names; see the 'tzselect' program supplied with this distribution for +one example. Names normally have the form AREA/LOCATION, where AREA is the name of a continent or ocean, and LOCATION is the name of a specific @@ -272,7 +296,7 @@ in decreasing order of importance: requires at least three characters for an abbreviation. POSIX.1-1996 says that an abbreviation cannot start with ':', and cannot contain ',', '-', - '+', NUL, or a digit. Draft 5 of POSIX 1003.1-200x + '+', NUL, or a digit. Draft 7 of POSIX 1003.1-200x changes this rule to say that an abbreviation can contain only '-', '+', and alphanumeric characters in the current locale. To be portable to both sets of @@ -397,8 +421,8 @@ Newsgroups: soc.genealogy.german Date: Tue, 9 Feb 1999 02:32:48 -800 Message-ID: <199902091032.CAA09644@netcom10.netcom.com> -The following is a(n incomplete) listing, arranged chronologically, of -European states, with the date they converted from the Julian to the +The following is a(n incomplete) listing, arranged chronologically, of +European states, with the date they converted from the Julian to the Gregorian calendar: 04/15 Oct 1582 - Italy (with exceptions), Spain, Portugal, Poland (Roman @@ -475,9 +499,9 @@ Gregorian calendar: 1760-1812 - Graub"unden -The Russian empire (including Finland and the Baltic states) did not +The Russian empire (including Finland and the Baltic states) did not convert to the Gregorian calendar until the Soviet revolution of 1917. -Source: H. Grotefend, _Taschenbuch der Zeitrechnung des deutschen -Mittelalters und der Neuzeit_, herausgegeben von Dr. O. Grotefend +Source: H. Grotefend, _Taschenbuch der Zeitrechnung des deutschen +Mittelalters und der Neuzeit_, herausgegeben von Dr. O. Grotefend (Hannover: Hahnsche Buchhandlung, 1941), pp. 26-28. |