Re: [LEAPSECS] Longer leap second notice, was: Where the responsibility lies

From: Ed Davies <>
Date: Tue, 03 Jan 2006 22:51:22 +0000

Poul-Henning Kamp wrote:
>> If we can increase the tolerance to 10sec, IERS can give us the
>> leapseconds with 20 years notice and only the minority of computers
>> that survive longer than that would need to update the factory
>> installed table of leapseconds.

Rob Seaman replied:
> No. Rather all computers that exist during such an event are
> obligated to deal with it. The number of deployed systems follows
> some increasing trend similar to Moore's law. By delaying the
> adjustments, you guarantee that more systems will be affected when
> they do occur. And, unless you can guarantee that a particular
> deployed system (and systems derived through various upgrade
> pathways) will be retired prior to the adopted horizon, prudent
> policy would require remediation in any event.
> Would like to see a proposed architecture a little more detailed than
> a "factory installed table".

PHK can reply for himself here but, for the record, I think RS's
reading of what he said is different from mine. My assumption is
that PHK is discussing the idea that leaps should be scheduled many
years in advance. They should continue to be single second leaps -
just many more would be in the schedule pipeline at any given

Obviously, the leap seconds would be scheduled on the best available
estimates but as we don't know the future rotation of the Earth this
would necessarily increase the tolerance. In theory DUT1 would be
unbounded (as it sort of is already) but PHK is assuming that there'd
be some practical likely upper bound such as 10 seconds.

Am I right in this reading?

Received on Tue Jan 03 2006 - 14:53:56 PST

This archive was generated by hypermail 2.3.0 : Sat Sep 04 2010 - 09:44:55 PDT