[LEAPSECS] Leap seconds have a larger context than POSIX

[Steve Allen]

On Wed 2020-02-05T15:32:54-0800 Tom Van Baak hath writ:
> I'm not sure it's fundamental to TAI that one must always, or only, use
> 24x60x60 radix notation. That's a useful convention in many cases, but at
> the h/w counter or s/w binary integer level radix notation is not required.

There were discussions about this in the early 1970s among members of
the CCDS and CIPM.  The USNO had been preferring a decimal count of
seconds, and this notion is pretty much what ended up in GPS.
Other members had other preferences, but in the end they made
no decision.

> Code should allow for a leap second event at the end of any month. The June
> / December thing is one of several guidelines for BIPM; it's not a rule that
> anyone writing UTC code should assume or depend on. Nor should code ever
> assume leap seconds are positive.

But the Soviets very much wanted not just any month, and they had
previously been using their own form of non-BIH UT2 for their own
different non-BIH rubber second UTC before 1972, and that looks like
why the CCIR directed BIH to issue the leap second 1972-12-31T23:59:60
early and exceed the 0.7 s limit.  Clearly the Soviets are no longer
in a position to insist again, but this whole arena seems well
described by Hector Barbossa telling Elizabeth Swan that the Pirate
Code is more like guidelines than actual rules.  Welcome abord the
Black Pearl.

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