On Sun, 6 Mar 2011, Joe Gwinn wrote: > > So, we have an instant in time that is forever fixed,
Yes. > and a progress rule that counts out uniform seconds (ideally SI seconds > the standard says in the Rationale). No. POSIX time does not define a progress rule. It is defined by a formula that maps UTC time labels into a flat counter. > The actual requirement is "As represented in seconds since the Epoch, > each and every day shall be accounted for by exactly 86400 seconds." That is a rephrasing of part of the defining formula. The preceding sentence is "How any changes to the value of seconds since the Epoch are made to align to a desired relationship with the current actual time is implementation-defined." What the two together mean is that the counter goes up by 86400 per day regardless of any adjustments to align the clock with "actual time" (whatever that means). > > What has been said many times is that it might be nice to change POSIX time > > to be based on TAI but if you try it you find that this breaks most > > timekeeping code. > > Why? Because the code assumes that the formula in section 4.15 gives the relationship between UTC and posix time. Tony. -- f.anthony.n.finch <[email protected]> http://dotat.at/ South-east Iceland: Westerly or southwesterly, becoming cyclonic in north for a time, 7 to severe gale 9. High. Rain or squally wintry showers. Moderate or good, occasionally poor. _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
