RE: [LEAPSECS] two world clocks

From: Seeds, Glen <Glen.Seeds_at_Cognos.COM>
Date: Fri, 21 Jan 2005 09:57:16 -0500

> -----Original Message-----
> From: Leap Seconds Issues [mailto:LEAPSECS_at_ROM.USNO.NAVY.MIL]
> On Behalf Of Poul-Henning Kamp
> Sent: January 21, 2005 3:40 AM
> To: LEAPSECS_at_ROM.USNO.NAVY.MIL
> Subject: Re: [LEAPSECS] two world clocks
...
> >... What
> >reliable evidence do we have that programmers are screwing up UTC
> >left-and-right?
>
> Until two years ago Microsoft Windows got it wrong for Denmark.

I can believe they got the time zone wrong. That has nothing to do with
leap seconds, and would not have been solved by abolishing them.

>
> UNIX has a continuous timescale with no room for leap seconds
> which is supposed to be "UTC".
>
The POSIX clock is explicitly and deliberately not aligned with UTC or
any other absolute time standard. Facilities for converting the system
clock to local time are implementation-specific.

This was not an oversight. Considerable analysis went into understanding
how this would work. The bottom line is that it's not a problem for all
but a very few applications, which have ways to work around it. These
same applications have timekeeping synchronization costs that are far
larger than the costs of these workarounds.

  /glen

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Received on Fri Jan 21 2005 - 06:57:42 PST