[tz] [PROPOSED 2/3] Simplify leapadd

Steve Allen sla at ucolick.org
Wed Jan 15 03:04:58 UTC 2020

On Tue 2020-01-14T18:23:02-0800 Paul Eggert hath writ:
> * zic.c (leapadd): Simplify by having one parameter CORRECTION
> instead of two parameters POSITIVE and COUNT (the latter always 1).
> The old code was for multiple adjacent leap seconds, a misfeature
> that was removed from zic.c in 2017c.

Do not forget that the original draft of CCIR Recommendation 460
allowed for leaps of "integral multiples" of one second.

The 1970 CCIR assembly documents are online at

The particulars of the change from allowing more than one leap second
to only one leap second are in volume 7 on page 116 at
and the connection between VII/1008 and Rec. 460 is on page 260.

The reasons why Study Group VII recommended a text allowing multiple
seconds are not evident, and neither are the reasons why Document
VII/1008 was amended on the floor during the Plenary Assembly, but
what the CCIR un-did in 1970 could still be re-done by ITU-R or a
sucessor agency.

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