bug#9794: 24.0.90; `format-time-string' no good for %Z

[Jason Rumney <jasonr@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: "Drew Adams" <drew.adams@oracle.com>
>> Date: Wed, 19 Oct 2011 00:43:28 -0700
>> 
>> And just because a non-Windows developer thinks that letting them
>> see "(Pacific Daylight Time)" is not useful to them and "()" is more
>> meaningful.  Sheesh.
>
> No, it's because a _Windows_ developer found out that the Windows
> time-zone names violate international standards for what %Z should
> produce, which breaks other Emacs features that use the results.

The international standards alone aren't a problem - GNU software in
general does not follow standards slavishly. The real problem is that
for many uses of time format strings (which correctly check for an empty
%Z string and use %z as a backup), in mail, news, HTTP headers, XML
documents and similar uses which rely on the strings being standards
compliant, the non-compliant long forms returned by Windows tzname()
cause real problems which are much more severe than the inconveniences
that this change has caused.

One proposal in that thread was to introduce a new format specifier to
print the long names (on non-Windows platforms it could output the
commonly used "Continent/City" format). Another proposal was that %EZ
could be used, which is especially fitting, for the Windows timezone
names, which are apparently locale sensitive (which was one of the
reported problems that led to them being removed in the first place).