Re: bug#641: format-time-string %Z does not work, starting with Emacs 22.2

[Ted Zlatanov]

On Wed, 6 Aug 2008 23:35:16 +0200 "Juanma Barranquero" <lekktu@gmail.com> 
wrote: 

JB> On Wed, Aug 6, 2008 at 21:53, Ted Zlatanov <tzz@lifelogs.com> wrote:
>> Does this help?  The Microsoft documentation linked by this article
>> implies that GetTimeZoneInformation() will DTRT.
>> 
>> http://www.chronos-st.org/Discovering%20the%20Local%20Time%20Zone--Why%20It%27s%20a%20Hard%20Problem.html

JB> It does return the "Microsoft timezone name", not Posix. In my system,
JB> it currently returns "Hora de verano romance".

On Thu, 07 Aug 2008 00:20:36 +0300 Eli Zaretskii <eliz@gnu.org> wrote: 

EZ> But this is a different problem.  The problem I wanted to solve is to
EZ> get something like JST+2JDT instead of "Jerusalem Daylight Time".  And
EZ> that cannot be solved by using Windows API, AFAIK, because the latter
EZ> is what Windows stores as the TZ name in its database.  In particular,
EZ> a test program that prints the TZ name returned by
EZ> GetTimeZoneInformation is the same "Jerusalem Daylight Time" that we
EZ> find in `tzname'.  I don't think RFC-822 compliant TZ names such as
EZ> EST-5EDT can be found anywhere in the Windows APIs and libraries, but
EZ> I'd be glad to be proven wrong.

We could build a database of known Microsoft timezones and map them to
ISO timezones.  It has to be done just once and then updated very
rarely--timezone names don't change often.  The full list of timezones
is in 

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones 

according to the article, so it may be possible to build the full list
of keys on a single machine and then fill it in with the mappings.

Ted