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Re: Draft for review: Working with Time Zones

From: Chris Lilley <chris@w3.org>
Date: Wed, 9 Feb 2011 13:11:27 +0100
Message-ID: <1952674509.20110209131127@w3.org>
To: John Cowan <cowan@mercury.ccil.org>
CC: "Phillips, Addison" <addison@lab126.com>, Richard Ishida <ishida@w3.org>, www International <www-international@w3.org>
On Tuesday, February 8, 2011, 5:49:22 PM, John wrote:

JC> Phillips, Addison scripsit:

>> > It's essential that this be rewritten to take leap seconds into
>> > account, as they say, early and often.  

>> Well, once or sometimes twice a year in certain years :-).

JC> Current provisions allow for a leap second at the end of any month,
JC> actually, and by the year 158421, we'll have to have a whole hour worth
JC> of leap seconds every day.

To put this in context; how many leap seconds have there been since the Jan 1970 epoch?

In other words, if two date-times are subtracted, one from now and one right at the epoch, without accounting for leapseconds, what is the total error currently?

OK, answering my own question

24 seconds.

And the time from atomic clocks differs from UTC by an additional 10 seconds, apparently.

So the total error from ignoring this is half a minute and counting.

 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Wednesday, 9 February 2011 12:11:31 UTC

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