Re: Predictable Internet Time

Harald Alvestrand <harald@alvestrand.no> Wed, 29 March 2017 21:35 UTC

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Subject: Re: Predictable Internet Time
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References: <m1cOYZ6-0000FAC@stereo.hq.phicoh.net> <bf1a0b49-6f76-1ec8-0a70-bfff9be40c16@alvestrand.no> <20170329155649.GS7490@localhost>
From: Harald Alvestrand <harald@alvestrand.no>
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Date: Wed, 29 Mar 2017 23:35:25 +0200
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On 03/29/2017 05:56 PM, Nico Williams wrote:
> On Wed, Jan 04, 2017 at 09:49:35AM +0100, Harald Alvestrand wrote:
>> FWIW, the W3C has switched to defining time inside a Web page in two
>> segments:
>> - Page load time, which is UTC-derived (POSIX time extended to
>> milliseconds), and can jump when the system clock is reset
>> - Events related to the page load time, which has floating-point
>> representation, and is guaranteed to be monotonic.
> But aren't these relative times (intervals)?  As long as they are short
> enough, distinctions between UTC, TAI, local, and smeared time will make
> little difference most of the time.  (Naturally, using local time might
> cause a page load time to appear to be negative, or over an hour, around
> daylight savings switch overs, or if one is moving across timezones,
> thus "most of the time".)
>
The first is an absolute time. The second is relative.


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