Joe Gwinn joegwinn at comcast.net
Sat Oct 10 19:51:22 EDT 2009

At 9:49 AM -0700 10/10/09, Steve Allen wrote:

>POSIX time is simply self-inconsistent as defined.

>Different commentators with different preferences cue on different

>aspects of the inconsistency.

POSIX Time as defined is self-consistent, but for various mostly good
reasons isn't what many people want, and there were protracted time
wars in the POSIX committee about what POSIX Time should and should
not be. There were many partisans, each loudly and intolerantly
proclaiming that only they possessed the One True Clock, while
ignoring the problems that any POSIX timescale must solve to be

The partisan fighting soon exhausted the Committee, who then threw
their hands up and mostly stuck with a slight cleanup of the prior
standard wording.

>I prefer to point out that no interpretation of POSIX time can

>be consistent with the legal time standard of all nations which

>was in contemporary use, as in the javascript here


I can well believe this. POSIX Time as used is neither TAI nor UTC.
In practice, this inconsistency matters little -- most people just
use NTP-distributed UTC from GPS receivers and get on with life.

>As such I do not expect that international standards bodies

>will ever be able to produce anything other than a compromise


The POSIX Committee threw the partisans out for a simple reason - the
partisans were screaming at each other and at the committee members
in timetalk, an obscure foreign language, and very few in the
Committee could even follow the arguments, let alone decide who to
agree with. Most committee members are experts in UNIX/Linux
operating system internals, know little to nothing of time, and have
little motivation to become experts in time. And they had bigger
fish to fry. So the Committee was forced to punt.

If the timefolk were to have their fights and bury their dead in
private, and only then have the survivors present a unified proposal
to the Committee, it might be possible to get the definition of POSIX
Time updated. The next opportunity to change is in about three
years, when the development of the next revision of the POSIX
standard will be undertaken.

Joe Gwinn

Vice Chairman, POSIX
Chairman, POSIX Realtime Subcommittee


>Steve Allen <sla at ucolick.org> WGS-84 (GPS)

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