IS0 8601 (the common date time notation used all over the net)
permits the hours to be between 00 and 24 (inclusive!).
<http://en.wikipedia.org/wiki/ISO_8601>
<http://www.cl.cam.ac.uk/~mgk25/iso-time.html>
As every day both starts and ends with midnight, the two notations
00:00 and 24:00 are available to distinguish the two midnights that
can be associated with one date. This means that the following two
notations refer to exactly the same point in time
and
In case an unambiguous representation of time is required, 00:00 is
usually the preferred notation for midnight and not 24:00. Digital
clocks display 00:00 and not 24:00.
and
ISO 8601 does not specify, whether its notations specify a point in
time or a time period. This means for example that ISO 8601 does
not define whether 09:00 refers to the exact end of the ninth hour
of the day or the period from 09:00 to 09:01 or anything else. The
users of the standard must somehow agree on the exact
interpretation of the time notation if this should be of any concern.
Just as KD3JF says below ... it gets more complicated the more you
think about it.
On Sep 9, 2007, at 6:46 PM, Augie Hansen wrote:
Paul Gates, KD3JF wrote:
What amuses me is when some hams use 2400 hrs... No such thing
IMO. There is 2359 and then 0000 hrs. At least that is what I
learned in the Army.
2400 is a legitimate synonym for 0000 in the 24 hour time system.
It can
be used as the specification of an ending time, but is not used as a
starting time. I write firmware for security systems and some other
dedicated systems that perform actions based, at least in part, on
date
and time data. 2400 is typically used to indicate the end of time
period
for the current day, such as 2100-2400 UTC. If it were specified as
2100-0000 there is an ambiguity (today or tomorrow?) that has to be
resolved by software. Using 2100-2359 produces a one-second shorter
than
desired period. Maybe not a big deal, but it could be in some
circumstances.
There is also another allowed value that might seem strange: a time
such
as 23:59:60 can occur when a positive leap second is inserted by a
leap-second event. Software needs to be aware of such situations and
deal with them intelligently.
It is truly bizarre that ARRL refuses to use the time
honored standard.
Agreed.
Gus Hansen
KB0YH
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Kevin Purcell
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