Michelle Konzack wrote: > Hello Maintainer, I am not the maintainer but as an interested party will contribute. :-)
> Is it right, that the 24h time > 2009-10-19 00:00:01 > which is one second after midnight, is realy > 2009-10-19 00:00:01 AM > in US-TIME format? Yes that is correct for US time. 00:00:01 is after midnight and before noon and is therefore "ante meridiem" meaning before mid day. After noon and before midnight is "post meridiem" or after mid day. Therefore 2009-10-19 00:00:01 is correctly AM. However use of "00" implies to me 24-hour time and 24-hour time has no need for either an AM or PM designation since it is unambiguous in that case. However if you were refering to 2009-10-19 12:00:01 and it is not known if it is 24-hour time or 12-hour time then the AM or PM is required to disambiguate them. > For me as I have learned in school for 30 years, the AM time is from > 00:00:00 in the morning to 11:59:59 noon and the PM time is from > 12:00:00 to 23:59:59 midnight. Noon and midnight are not strictly either a.m. or p.m. since they are the exact times of meridian crossing. The issue is in dispute by different conventions. In the U.S. two conventions are popular. 1) Never using a.m. or p.m. with noon or midnight. Instead use 12 noon or 12 midnight. Personally I think it is improper to apply a.m. or p.m. to either noon or midnight as at that moment it is neither before nor after meridian passage. 2) Use of 12:00 a.m. meaning midnight and 12:00 p.m. meaning noon. The thinking being that time moves forward and asymetrically the moment is not static and at that moment the time is immediately the next period so chooses the next description. Much of this issue is nicely captured on the wikipedia page. http://en.wikipedia.org/wiki/12-hour_clock#Confusion_at_noon_and_midnight Note that airlines, trains and busses (at least in the US) *never* schedule any arrival or departure at either noon or midnight. It would be too confusing for the average or lessor person. To avoid confusion arrivals and departures near noon and midnight are always scheduled at least a few minutes on one side or the other so as to be absolutely clear which day and which time is meant. The issue of a.m. and p.m. application to noon and midnight is always avoided. > The output of "date" is realy confusing. I disagree about date but I agree that clock time and calendar dates are very confusing. They are human constructs that have evolved over many years and cannot be understood without also knowing the long history that has created the present system. Perhaps if you were to include an example of what you are trying to do then suggestions could be provided to remove the confusion? Bob
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