Ashley Yakeley ashley at semantic.org
Thu Jan 27 03:09:17 EST 2005

In article 
<3429668D0E777A499EE74A7952C382D1030DE110 at EUR-MSG-01.europe.corp.microso
 "Simon Marlow" <simonmar at microsoft.com> wrote:

> I like the idea of having a single notion of absolute time, which is
> independent of TAI or UTC time.  You can do arithmetic on absolute time
> (add/subtract absolute units of time, find absolute time differences),
> and convert to/from TAI and UTC.
> My library happens to keep absolute time as TAI seconds since the epoch,
> but it doesn't have to.  A representation using (days,ticks) sounds like
> it might be hard to do arithmetic on, though.

I think your ClockTime is a sensible way to represent absolute time for 
TAI. But we also need something that represents (for instance) 
"2008-08-03 11:00:00 UTC" even though we don't know what precise TAI 
time that will be. For this I would consider using a (days,ticks) pair: 
it allows you to do arithmetic such as "5 UTC days later" and end up 
with the expected answer even when there are intervening leap seconds.

Ashley Yakeley, Seattle WA

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