[tz] [tz-announce] 2018f release of tz code and data available
c933103 at gmail.com
Mon Oct 22 00:50:54 UTC 2018
I can't see the problem here. For instance, Japan is now using UTC+9, so
the leap second take place right before 9am(00:00:00Z), yet 10am that day
would still unambiguously mean 10am(01:00:00Z). I cannot see why it would
be a problem for UTC after 24z.
2018-10-22 05:25, Michael H Deckers via tz <tz at iana.org> wrote:
> On 2018-10-21 03:00, Steve Allen wrote:
> > Many examples of non-normalized dates and times exist in historical
> > literature.
> For time stamps of UTC, or of a time scale derived from UTC
> with a piecewise constant offset (as for civil time scales),
> time-of-day values on or after 24 hours may be ambiguous due
> to leap seconds.
> The fictitious UTC time stamp "2016-12-31T25Z" could
> indeed be taken to mean
> 2016-12-31T00Z + 25 h = 2017-01-01T00:59:59Z or else
> 2017-01-01T00Z + 01 h = 2017-01-01T00:00:00Z.
> That is probably one reason why the draft new version
> of ISO 8601 proposes to drop even the notation for the time
> of day 24 h after midnight (does "2016-12-31T24Z" mean
> 2016-12-31T23:59:60Z or 2017-01-01T00:00:00Z?).
> It is true that this ambiguity can arise at most for two
> (or twelve) dates in a year, but a parser for zic input
> has to deal with all cases, and cannot be written correctly
> unless the notation is defined unambiguously.
> There is no such ambiguity with day of the month numbers
> less than 01 or > ultimo, so that it is always possible
> to avoid any time-of-day values below 00 h or on or after 24 h
> in time stamps of UTC or of civil times.
> Michael Deckers.
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