Re: [Ntp] Leap second draft

[Steve Allen <[e-mail]>]

This is the second message to Daniel Franke.

On Fri 2019-03-29T21:59:28-0700 Steve Allen hath writ:
> >           While neither TAI nor UTC is formally defined for any date
> >    earlier than the epoch, this nit is routinely ignored by allowing the
> >    day number to be negative and by assuming the fiction that prior to
> >    1958 Earth's rotation was always perfectly regular with respect to
> >    proper time.
>
> Which epoch?  POSIX epoch?
> Any date at which there is general agreement among all parties
> about when it happened is an epoch.  Please be specific and
> never use merely "the epoch".

To expand on my objection here, I find these sentences to be
unconnectable to any concrete concepts.

There is a common strategy in time scales which are trying to be a
precision time scale now, but which also wish to extend themselves
simply to an era before there was precision.

As such time scales are extended backwards in time there is some
past epoch at which the scale switches tracks and connects itself
to just plain Universal Time.  So such time scales are counting
SI seconds now, but going into the past they switch to counting
mean solar seconds.

They do not presume that the mean solar seconds were perfectly
regular, they just change from one kind of second to the other.

For radio broadcast time signals the change happened 1972-01-01
because that is what the CCIR said in Recommendation 460.

For Microsoft Windows the change happened 2018-06-01 because
that is what Microsoft said is the date that they begin to
distribute TAI offset from UTC so that Windows boxes can
count subsequent leap seconds.

--
Steve Allen                    <[e-mail]>              WGS-84 (GPS)
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