[LEAPSECS] Windows Server 2019

[Steve Allen]

On Mon 2018-07-23T13:18:22-0600 Warner Losh hath writ:
> In the absence of setting a local time for the leap
> second, the offset is controlling and therefore it happens at UTC midnight,
> since it's definitely and unambiguously defined in ITU-R TF 460-6 as such
> (all known earlier revisions too, I believe was the conclusion when a
> similar issue was raised years ago on this list, though I think -3 was the
> oldest that could be found at that time).

We have managed to obtain scans of varying rattiness of all versions.
More interesting than the versions themselves are the related
recommendations (some since withdrawn) and the transcripts of the
discussion in the voting sessions.  Those give some clues into
what had and had not been presented to the general assembly in
order to motivate their approval of the new versions.  E.g.,
from 1974 through 1997 the ITU-R recommeded using either UTC
or TAI as appropriate.
https://www.itu.int/rec/R-REC-TF.485/en

CCIR Rec 460 had no details other than 1 second leaps.
This original (version "0") Rec was reprinted in various places
including by US NBS in Monograph 140, so it is online in scanned
documents.

The rules were worked out in CCIR Report 517 (Question 1/7, Resolution 53)
by Study Group 7 during 1971-02-17/23.  This put the leap second at UTC
midnight.  It is also reprinted in NBS Monograph 140.

This was incorporated into Rec 460-1 by the CCIR general assembly
between 1971-02-17/23 and remains the same in all subsequent revisions.

CCIR and ITU-R documents mention UTC, UT[012], and TAI, and they refer
the reader to other agencies for definitions of those terms.
They do not mention local civil time,

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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