ISO 14652 draft on POSIX date/time/tz

Joseph S. Myers jsm28 at
Mon Jul 5 17:45:45 UTC 1999

On Sun, 27 Jun 1999, Markus Kuhn wrote:

> Those of you interested in upcoming ISO standards related to date/time/
> timezone APIs for POSIX systems should have a look at

The first thing I wonder about this is what implementation experience
there is of including timezone specifications in the locale specification
as this does?  After all, when C9X revisions were being discussed it was
insisted that any significant new features should be based on previous
implementation experience!

However, more generally there seem to be several problems with the
specification in this area; it doesn't define what a timezone is, and
states both that each string defines a timezone and that standard and
summer time are separate time zones (and if `time zone' and `timezone' are
distinguished, this is a very bad idea, though it has precedence in
POSIX.2 drafts - see E.2.2.2 on the former use of `file name' and
`filename'); it is unclear about why you might define multiple timezones
within a locale, whether they represent different geographical areas or
variations in historical behaviour; it does not improve on POSIX.1 by
allowing for `Sunday after the third Saturday'; and it is very unclear how
to specify single and double summer time in a single year.  Also the use
of what would seem to be a US date format for dates in the rationale,
rather than an ISO 8601 format, betrays at the very least bad editing.
The example for Denmark, through not attempting to specify historical
behaviour, fails to clarify these matters at all (and appears to be
actually wrong in (not) specifying the times of changes between standard
and summer time, since the defaults do not correspond to the EU rules).

Joseph S. Myers
jsm28 at

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