"Dave Cantor" wrote on 2006-04-22 22:34 UTC:
On 22 Apr 2006 at 16:06, Oscar van Vlijmen wrote:
DST [for Guatemala] starts on Sunday, April 30, 2006 at 12:00 Midnight local standard time DST ends on Sunday, October 1, 2006 at 12:00 Midnight local daylight time
I am not commenting on the veracity of the cited material at all, and I quote Oscar only because the quotation serves as an example.
I'm not even sure that people on this list are the right ones to complain to, but surely most everyone on this list, must have noticed the ambiguity.
I am troubled by the specification of midnight on a certain date.
In the old days (and by that I mean roughly before computers were commonly used by non-computer-geeks like us) to keep time, "midnight Tuesday" meant the minute after 11:59 p.m. Tuesday night. I think (but am not sure) that most people still mean that when they say "midnight Tuesday". Midnight _used_to_be_ a synonym for 2400 hrs., the end of the day.
But we pretty much don't use 2400 hrs. any more, and "midnight" has become a synonym, in some contexts, for 0000 hrs., the start of the day. So "midnight Tuesday" might refer to the minute before 12:01 a.m. Tuesday morning (Monday night!).
Is anyone else concerned? What should be done? Who should do it?
Government officials who use obsolete and ambiguous terms such as "12:00 midnight" should be gently pointed to the relevant official standards for time notation, which have solved this problem adequately and unambiguously. ISO 8601: 00:00 is midnight at the start of the given date 24:00 is midnight at the end of the given date (= 00:00 of the next day) All this is discussed in great detail, for example, at http://en.wikipedia.org/wiki/12-hour_clock http://en.wikipedia.org/wiki/24-hour_clock http://en.wikipedia.org/wiki/Midnight http://en.wikipedia.org/wiki/ISO_8601 -- Markus Kuhn, Computer Laboratory, University of Cambridge http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain