[LEAPSECS] BBC radio Crowd Science

[Brooks Harris]

On 2017-01-31 12:33 PM, Warner Losh wrote:
> On Tue, Jan 31, 2017 at 7:54 AM, Steve Summit <scs+ls at eskimo.com> wrote:
>> Tom Van Baak and Michael Decker wrote:
>>>>> 2017-01-01T00:00:36.5 - 36 s = 2016-12-31T23:59:60.5
>>>> What kind of arithmetic is that?
>> I think it ends up being roughly the same kind of arithmetic
>> that tells you that the 60th day of the year is March 1.
>> Or maybe February 29.
> Maybe he's referring to the fact that the offset is 37s, not 36s. The
> offset changes AT THE START OF THE LEAP SECOND.
OK, now here's something I've been worrying about for a long time. 
Everyone on LEAPSECS, and seemingly everywhere else in the literature, 
are *sure* they know exactly what UTC with Leap Seconds is. Yet the 
specifications are unclear, as we've been discussing.

Here you are saying "The (TAI-UTC) offset changes AT THE START OF THE 
LEAP SECOND. " That is in direct conflict with my best understanding of 
it. I'd say "The (TAI-UTC) offset changes immediately AFTER the Leap 
Second, at the midnight roll-over to the first second of the next 
month." (See other email with my explanation and demonstration code).

So, this is obviously a huge interoperablity issue. It has ramifications 
through many aspects of timekeeping manipulations.

Ah, so who's right?

-Brooks