Re: [LEAPSECS] Rubber seconds

From: Poul-Henning Kamp <>
Date: Fri, 05 Aug 2005 16:58:07 +0200

In message <>, Ed Davies writes:
>Poul-Henning Kamp, replying to Markus Kuhn, wrote:

>Why do you write this when I've just given a examples
>of cases where rubber seconds are usable? It might
>help if you could explain what you think is wrong with
>my examples.

1. It is agreed that there are applications for which
    rubber seconds are unsuitable.

2. Any use of rubber seconds will therefore only be
    for some limited subset of applications.

3. There is no way in hell we can prevent applications
    of the two kinds from interacting.

4. It follows therefore logically that any kind of rubber seconds
    will introduce a new interface across which time will have to
    be translated from rubber to SI seconds.

5. You have just introduced yet another place where computers
    and people can and will get timekeeping wrong.

6. We are trying very hard to avoid interfaces where time can
    be messed up or confused.

QED: rubber seconds in any shape or form will only make the problem
worse and not better.

>Please note that I'm not suggesting that rubber seconds
>are good in all cases: just that there are some
>circumstances where they are acceptable and, maybe,
>preferable to having non-monotonic times or times like

There is nothing non-monotonic about it.

We just need (much!) longer notice about when it happens
to handle it properly in computers.

>Remember that this is a list for the discussion of the
>future of leap seconds. Any answer which simply assumes
>that leap seconds should go away is rather missing the

I'm very much not assuming leap seconds go away.

I'm totally open to any kind of timekeeping that works sensibly.
I can live with leapseconds, leap minutes and leap hours, as long
as I get sufficient warning (preferably 50 years, see my earlier
email on this).


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Received on Fri Aug 05 2005 - 07:58:19 PDT

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