On Mon, 2020-11-16 at 10:29 +0000, Michael H Deckers wrote:
On 2020-11-15 23:21, John Sauter wrote:
If I am reading section 9.4 correctly, they are defining two time scales: the old scale (before the leap second) and the scale after the step. In the old scale the leap second at the end of 2016 would start at 2016-12-31T24:00:00 and end at 2016-12-31:24:00:01. In the scale after the step the leap second would start at 2017-01-01:00:00:-1 and end at 2017-01-01T00:00:00.
Yes.
The rationale of a positive leap second notation for a time point is to indicate that the point does not belong to the normal range of datetime values, where there are only 20 seconds from 2016-12-31T23:59:50 to 2017-01-01T00:00:10. One therefore has to use a notation that cannot be confused with notations that are used for these normal datetime values.
Exceeding the normal range [0..1[ d of time of day is one method; the ITU method uses times of day >= 1 day, but times of day < 0 d could similarly be used. Other means would be affixes to the notation (such as the leap second bit in the Ada programming language, or the labels "A", "B" proposed to distinguish duplicate timestamps during fall back from summer time in Denmark and Germany).
Michael Deckers.
In addition, following Steve Allen's suggestion, the start of the leap second in the time scale after the step could be 2017-01-00T23:59:59. John Sauter (John_Sauter@systemeyescomputerstore.com) -- PGP fingerprint E24A D25B E5FE 4914 A603 49EC 7030 3EA1 9A0B 511E