[tz] [PROPOSED 2/3] Simplify leapadd

Steve Allen sla at ucolick.org
Wed Jan 15 15:53:04 UTC 2020

On Wed 2020-01-15T11:28:35+0000 Michael H Deckers hath writ:
> Isn't that obvious? If UTC cannot deviate from UT1 by more than 0.7 s
> (as Recommendation 460 originally stipulated) then UTC cannot
> have leaps by more than 1.4 s. Leaps by N s are only possible when
> |UTC - UT1| is allowed to be >= N/2 s.
> The draft version of Study Group VII (the one that allows for leaps
> in UTC by an integral number of seconds) specifies no bound
> for |UTC - UT1|.

The original version of CCIR Rec. 460 did not specify any bound.
See volume 3 page 227
The draft with "integral multiples" was pushed through in a rush in
1970 January because of an imminent political deadline from Germany
and other political pressure from USSR.

The technical details with max 0.7 second deviation came from Report
517 which was not forged until 1971 February and included into the
CCIR volume 3 as addendum starting on page 258a.  That 0.7 limit was
disregarded in less than two years also due to Soviet political
pressure, leading to a rewrite that gave the limit of 0.8 second even.
though the 0.7 limit had already been hard-coded into the format of
the broadcast time signals.

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