RE: [LEAPSECS] pedagogically barren?

From: Seeds, Glen <Glen.Seeds_at_Cognos.COM>
Date: Thu, 5 Jun 2003 09:22:51 -0400

The "modern" (formally, "24-hour") notation is as common as the 12-hour form
in Quebec and France. That's probably the worst possible situation, as you
never know what time "9" means. (Quebec is a little better, as the written
form 9h00 always means 9AM ).

Actually, date is much worse than time, notation-wise, as there are 3 common
interpretations for 01/02/03 (010203 in compressed form):
 YYMMDD: 2001 Feb 3 (monotonic, sorts correctly, ISO standard)
 DDMMYY: 1 Feb 2003 (monotonic, but sorts incorrectly)
 MMDDYY: Jan 2 2003 (mixed)
The most perverse of these is MMDDYY, which is the norm in the US. (The
common US date-month form is MMYY.)

All of this is still off-topic for this forum, though.

-----Original Message-----
From: Markus Kuhn [mailto:Markus.Kuhn_at_CL.CAM.AC.UK]
Sent: June 5, 2003 5:33 AM
Subject: Re: [LEAPSECS] pedagogically barren?

"Seeds, Glen" wrote on 2003-06-04 15:00 UTC:
> It's also true that changing to SI units for weight and volume is a lot
> technically tractable than for length. Public opposition would still be a
> big barrier, though.

That's what the UK have done. The imperial units of weight and volume
are not legally recognized any more in Britain (only pints are still
permitted for drinks volume), whereas inch/yard/mile continue to be
legally recognized for length and speed.

To bring the topic closer back to the scope of this mailing list:

One international standard related to time keeping that I would like to
advertise for is the international standard numeric date and time
notation (ISO 8601), i.e. 2002-08-15 and 14:14:57.

Whereas both the modern 23:59:59 and the old fashioned 11:59:59 p.m. are
equally widely used in Britain, the modern notation seems to be mostly
in the US outside the military and scientific communities (and the US
military seem to drop the colon as in "1800" and say strange things like
"eighteen hundred hours" instead of "eighteen o'clock"). The uniform
modern 00:00 ... 23:59 notation is now commonly used in Britain for
almost any publically displayed timetable (bus, trains, cinemas,
airports, etc.), and on the Continent they haven't used anything else to
write times for many decades.

The modern notation is not only shorter and much easier to do mental
arithmetic on, it also provides an unambiguous distinction between
midnight at the start of day (00:00), noon (12:00) and midnight at the
end of day (24:00), whereas the meanings of "12:00 a.m." and "12:00 p.m."
are rather ambiguous. I really wonder, why the modern notation doesn't
catch on in the US, where even air travel tickets still use the awkward
notation (and solve the ambiguity problem by never scheduling any event
exactly on noon or midnight).

More information on ISO 8601:


Markus Kuhn, Computer Lab, Univ of Cambridge, GB | __oo_O..O_oo__
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Received on Thu Jun 05 2003 - 07:15:14 PDT

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