TAI zone?

Tim Parenti tim at timtimeonline.com
Fri Jul 1 14:33:34 UTC 2011

On Fri, Jul 1, 2011 at 06:35, Guy Harris <guy at alum.mit.edu> wrote:

> So what does civil time do during a positive leap second?  Tick the seconds
> counter from 59 to 60, to match UTC's seconds counter?  Tick the seconds
> counter from 59 to 00, so it's off from UTC's seconds counter, and then
> maybe get fixed up later?  Freeze during the leap second, and tick from 59
> to 00, so that, except during the leap second, it matches UTC?

At least nowadays, civil time in most (but certainly not all) countries is
tied to UTC.  This would imply that, for all legal purposes, the minute
2008-12-31T23:59Z did indeed have 61 seconds.  If a contract were to have
expired in the U.S. at, say, 17:00:00 MST (UTC-07:00) on 31 December 2008,
it is my understanding that you would indeed still have that extra second at
16:59:60 MST to register a new one.

That would be the technical answer.  For all *practical* purposes, how
exactly that extra second is handled by the big clock in the town square or
by the clerk with whom you register the new contract is inconsequential; or
rather, it is beyond the scope of the TZ database.  Whether they account for
it, "freeze", let the clocks "slip", or simply correct it later, that's an
issue of *accuracy* — not an issue of *timescales*.

On Fri, Jul 1, 2011 at 10:09, Tony Finch <dot at dotat.at> wrote:

> De jure yes, but it is de facto UTC. GMT hasn't been maintained for
> decades and almost all the UK government-sponsored time signals provide
> UTC without DUT1.
> The UK government wishes to keep leap seconds.
> http://www.whatdotheyknow.com/request/uk_policy_on_leap_seconds
This is true.  In the UK, "GMT" is used more often as a synonym for UTC
these days for what basically amounts to "patriotic" reasons.  Not exactly
correct terminology, but we deal with it.

Tim Parenti
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