[tz] What's "right"?

Paul Gilmartin PaulGBoulder at AIM.com
Mon Nov 16 21:11:50 UTC 2020

On 2020-11-16, at 11:44:07, Michael H Deckers via tz <tz at iana.org> wrote:
>    A positive leap second is usually taken to be a (left closed
>    and right open) interval of length 1 s of TAI values that
>    are not associated with UTC values by the function from UTC
>    to TAI as published by the IERS. For the latest leap second this
>    interval was [2017-01-01T00:00:36..2017-01-01T00:00:37[;
>    while TAI was in that interval, UTC could be 36 s or 37 s
>    less than TAI, and ITU recommends the use of their leap second
>    notation for the value of UTC.
Is that the same as?:

 A positive leap second will be introduced at the end of December 2016.
 The sequence of dates of the UTC second markers will be:		
                          2016 December 31, 23h 59m 59s
                          2016 December 31, 23h 59m 60s
                          2017 January   1,  0h  0m  0s

The UTC "23:59:60" is extraordinary; I'd call it the "leap second".
A "negative leap second" is problematic.  It would be a TAI second
with no matching UTC second.

-- gil

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