Time Zone Localizations

Mark Davis mark.davis at jtcsv.com
Sun Jun 13 19:42:13 UTC 2004

Well, here's something like what a spec would be. A document with a stable link,
e.g.  ftp://elsie.nci.nih.gov/pub/olson_timezone_specification.html, that
describes (not necessarily in order):

1. What are the all valid Olson TZIDs (not necessarily a list in the document,
but it should be possible to point to a single file that contains that list, in
a well-described format).
2. How to determine which are 'canonical' and which are simply included for
3. What is the meaning of an TZID
4. What is the versioning scheme, including assurance that:
    - once a version is issued it is never changed.
    - TZIDs are stable, in the sense that they will never be withdrawn or reused
with a substantially different semantic in later versions
5. An explicit description of the data representation for all of the data files.
It should include common features, such as that data on each line after # is a
comment. It should be possible from the document to understand the format of all
of the data files, completely independent of any code. Again, this can be
indirect: e.g. The data format for the zone.tab file is described in the header
of that file.

It should be possible to read this document directly -- and the lists in #1 and
#2 -- instead of hunting around in compressed files for all the pieces.

A lot of the material for the above are present, someplace on the site. For
example, much of #3 could come from the information in the Theory file from
"----- Names of time zone rule files -----" up to "----- Calendrical
issues -----", but should be reworded somewhat to remove phrases like "When this
package is installed,".

► शिष्यादिच्छेत्पराजयम् ◄

----- Original Message ----- 
From: "David Keegel" <djk at cybersource.com.au>
To: "Mark Davis" <mark.davis at jtcsv.com>
Cc: "Paul Eggert" <eggert at CS.UCLA.EDU>; <tz at lecserver.nci.nih.gov>
Sent: Sun, 2004 Jun 13 00:49
Subject: Re: Time Zone Localizations

> There are general rules for choosing TZID names and various other things
> in the "Theory" file within tzdata.
> I'm not sure if that helps Mark, because I'm not really clear on exactly
> what sort of specifications he is looking for.
> But in any case, newcomers seem to have difficulty finding things like
> the naming conventions in the Theory file.  It might be worth putting
> pointers to the Theory file from tzcode and the zone.tab file from tzdata
> in places like
> http://www.twinsun.com/tz/tz-link.htm
> and maybe the README for tzcode.  Perhaps there should even be a short
> README for tzdata and/or ftp://elsie.nci.nih.gov/pub/.
> ] The latter is what we need; it needed be a long document, and I'd be glad to
> ] together a draft for your consideration.
> ]
> ] Mark
> ] __________________________________
> ] http://www.macchiato.com
> ] ___ _______________________________________________________________ ___
> ]
> ] ----- Original Message ----- 
> ] From: "Paul Eggert" <eggert at CS.UCLA.EDU>
> ] To: "Mark Davis" <mark.davis at jtcsv.com>
> ] Cc: <tz at lecserver.nci.nih.gov>
> ] Sent: Fri, 2004 Jun 11 23:33
> ] Subject: Re: Time Zone Localizations
> ]
> ]
> ] > "Mark Davis" <mark.davis at jtcsv.com> writes:
> ] >
> ] > > we can't point people to a document that they can read, that
> ] > > describes a specification.
> ] >
> ] > I don't see why not.  If you want a list of Olson TZIDs, you can make
> ] > a copy of zone.tab, and point people at it.  Or if you want the
> ] > specification for the zic input file format, you can make a copy of
> ] > the zic man page, and point people at that.  This stuff is all in the
> ] > public domain.
> ] >
> ] > On the other hand, if the existing documentation is not enough for
> ] > your needs, then it might be helpful if you could write something that
> ] > will do the job, and contribute it back to the mainline distribution.
> ] > Documentation is often the hardest job in volunteer efforts like
> ] > these, and I'd welcome any good contributions in this area.
> ___________________________________________________________________________
>  David Keegel <djk at cybersource.com.au>  http://www.cyber.com.au/users/djk/
>  Cybersource P/L: Linux/Unix Systems Administration Consulting/Contracting

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