1433Re: Dates with timezone information
- Jan 14, 2006--- In ISO8601@yahoogroups.com, NGUYEN Ivy <nguyenivy@g...> wrote:
> I think you just indicate whatever default time you use (like 00:00),I don't understand this last comment. Obviously, any date and time you
> then use a timezone afterwards. I don't believe dates alone have
> timezone information in ISO 8601. It wouldn't make sense, unless some
> new provision is added like 'all dates without times that have
> timezone information, are to be treated as 00:00 if no time is
> It is true that giving a date without a timezone can cause ambiguity,
> as at least half the world is always a different date than stated. But
> on the flip-side, if no time within the date is stated at all, than
> how can we have timezone information? '2000-01-01 in New York
> (UTC-05)' means that 24-hour period lasting from 00:00--24:00 in New
> York (timezone). Doesn't reveal much more.
specify is a range, if you want to view it that way. If, as you say,
we can view "2000-01-01" is the range [2000-01-01 T00:00, 2000-01-01
T24:00), then the time "2001-01-01 T20" could also be seen as the
range [2001-01-01 T20:00, 2001-01-01 T21:00).
Any time we represent will be specified to some amount of precision.
Just providing the date is one level of precision. Specifying the hour
is a higher level of precision, and indicating minute and second give
even higher precision. Since the ISO standard doesn't say whether to
interpret a date as a time range or as a singular point in time, that
is up to the application as far as I am concerned. Why then should you
draw a line at which precision level time zones are used?
If I choose to view a date as a singular point in time (much as many
would view T20:01:02 as a singular point), then that moment will occur
at a different local time in different time zones. Obviously we could
specify at which second it occurs, as in "The Swedish new year occurs
on 2006-01-01 00:00:00+01:00 and the Chinese new year occurs on
2006-01-29 00:00:00+08:00", but it is much more convenient to say "The
Swedish new year occurs on 2006-01-01+01 and the Chinese new year
occurs on 2006-01-29+08".
Perhaps the issue at hand here boils down to what is the purpose of
introducing reduced precision into the ISO standard in the first place.
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