Re: what is broken?

From: Glen Seeds <Glen.Seeds_at_COGNOS.COM>
Date: Wed, 18 Oct 2000 19:49:24 -0400

This group should not conern itself overly with POSIX - they are managing
their own affairs. FYI, the wording just adopted by the Austin Group for the
revised POSIX standard is as follows:

The relationship between the actual time of day and the current value
for Seconds Since the Epoch is unspecified.

How any changes to the value of Seconds Since the Epoch are made
to align to a desired relationship with the current actual time
are made is implemetation-defined. As represented in Seconds Since the
Epoch, each day shall be accounted for by exactly 86400 seconds.


The topic of whether Seconds Since the Epoch should account for leap
seconds has been debated upon a number of occasions, and each time
consensus was reached (with acknowleged dissent each time) that the
majority of users are best served by treating all days identically.
(That is, the majority of applications were judged to assume a single
length (as measured in Seconds Since the Epoch) for all days.) Those
applications which do care about leap seconds can determine how to
handle them in whatever way it felt was best for that application. This
was particularly emphasized because there was disagreement about what the
best way of handling leap seconds might be. It is a practical impossiblity
to mandate that a conforming implementattion must have a fixed relationship
to any particular official clock (consider isloated systems, or systems
performing "reruns" by setting the clock to some arbitrary time).

Note that as a practical consequence of this, the length of a second
as measured by some external standard is not specified. Applications
must be matched to a system that provides the particular handling of
external time in the way required by the application.
Received on Wed Oct 18 2000 - 16:59:28 PDT

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