Re: [Tzdist] Getting to closure Re: [tzdist] #31 (service): Include leap seconds?

[Steve Allen <[e-mail]>]

On Sat 2014-12-13T11:39:22 -0500, Ken Murchison hath writ:
> For those that are interested, I have added an Etc/TAI time zone to
> my test server.
>
> Full VTIMEZONE: https://cyrus-test.andrew.cmu.edu/tzdist/zones/Etc/TAI
>
> Observances: https://cyrus-test.andrew.cmu.edu/tzdist/zones/Etc/TAI/observances?start=1970-01-01T00:00:00Z&end=2038-01-01T00:00:00Z

That's nice to see that the tzdist protocol is handling the data.
It might be good to think about how that might be tweaked for
applications that want an answer other than zero between 1970 and
1972, but that is already problematic because TAI did not exist with
that name until 1971.  There is no right answer for proleptic cases
extending back as far as some of the zones which have been in tzdata.
And this is not relevant for tzdist.

I think that leaves the issue of including leap seconds in tzdist as a
name space issue, and that is explicitly outside the scope of the
draft.

However, it could be helpful to add a paragraph explaining that some
publishers may include zones where the time offsets are based on the
actual broadcast specification for the number of seconds which have
occurred in UTC as published by the ITU-R.  Those zones would be used
for systems where the underlying time scale does count leap seconds,
in contrast to POSIX time which does not count leap seconds.  Such a
paragraph should note that client programs using those zones will need
extra code to handle the leap second information.

If such a paragraph be included then it should include references to
1) the IANA tzdata and tzcode for the "right" zones
2) the ITU-R document defining UTC.  There is already an example for that
in informative reference 6 of RFC 7164
 [6]  ITU, "Standard-frequency and time-signal emissions", ITU-R
      TF.460-6, February 2002,
      <http://www.itu.int/rec/R-REC-TF.460/>.
3) the IERS publication Bulletin C which announces leap seconds, also
as seen in reference 12 of RFC 7164
 [12]  IERS Earth Orientation Centre, "Bulletin C - Product metadata",
       <http://datacenter.iers.org/web/guest/eop/-/somos/5Rgv/product/16>.

But in any case I think that tzdist issue #31 is already handled by the
protocol in the draft.

--
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