As Joe Reid (I think) has pointed out, it depends on the context. Although 24-hour clocks don't display 24:00, expressing midnight as 24:00 is explicitly permitted by ISO 8601:1988 as an alternative to 00:00 -- in emphasizing the completion of one day, for example, rather than the beginning of the next.
I haven't checked ISO 8601:2000, as I don't have a copy. However, Markus Kuhn's web site (accessible from http://metric1.org/dateandtime.htm) contains the following: 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: 1995-02-04 24:00 = 1995-02-05 00:00 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. Bill Potts, CMS Roseville, CA http://metric1.org [SI Navigator] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Carter, Baron Sent: Wednesday, January 02, 2002 05:23 To: U.S. Metric Association Subject: [USMA:17123] RE: Celebrations in Maastricht There is no 24:00 hours. It goes 23:59, 00:00, 00:01 etc. Regards Baron Carter -----Original Message----- From: Han Maenen [mailto:[EMAIL PROTECTED]] Sent: Monday, 31 December, 2001 12:52 To: U.S. Metric Association Subject: [USMA:17023] Celebrations in Maastricht To-night, on this special New Year's Eve there will be a large celebration in Maastricht to welcome the euro and it will be on TV. It was in this small city that in 1992 the decision was taken to adopt the euro on 2002 January 1. At exactly 24:00 hours the euro will replace the guilder as the legal currency. But people can still pay with their old currency for some time, in our country till January 28. Han
