[tz] leap-seconds.list format

[Tim Parenti]

On Tue, 6 Feb 2024 at 17:26, Byron Torres via tz <tz at iana.org> wrote:

> Recently it seems the IERS has changed the format of the
> leap-seconds.list file they serve[1], from the old format by NIST[2].
> The comments are reworded, the lines wrap at a large width, and most
> importantly, the whitespace between the decimal timestamps and
> time-differences, previously a tab, have been replaced with spaces.
>

I believe you're misunderstanding what has actually happened here.  To be
clear: neither IERS nor NIST has (significantly) changed how they have
been publishing their respective leap-seconds.list files.  You are probably
instead seeing the effects of tzdb's recent switch from republishing the
NIST flavor of this file, which uses tabs, to republishing the IERS flavor,
which uses spaces.

You can see that the changes to the IERS flavor of leap-seconds.list have
actually been quite modest over the last ~9 years by listing the ntp/
directory and comparing:
https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.3637008000 from
2015-04-03 with
https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.3913697179 from
2024-01-09
In particular, spaces have been used consistently by IERS, and the comments
have only changed in a few minor rewordings and typos over the years.

On the other hand, the NIST flavor has had tabs for at least the last
decade.  Although they don't keep old versions available on FTP, you can
see tzdb's captured history of the NIST version of the file here:
https://github.com/eggert/tz/commits/27b4d76d1f6f9987bedb4e0b16369779020a9c97/leap-seconds.list

As Paul has already mentioned, we recently made the switch from the NIST
flavor to the IERS flavor after much discussion because the latter is
ultimately a more reliable, authoritative source.  Case in point: While
IERS published a new version of the file alongside their most recent
2024-01-09 announcement, today — nearly a month later — NIST's latest
version is still dated 2023-08-06.

While all of that renders a few of your original questions about
motivations moot, more good information on the format expected by ntpd has
been provided in the other replies.


> * Could at least the spaces be changed back to tabs?


For the reasons already discussed, this is unlikely.  IERS have been using
spaces consistently for quite a while.

The other data files distributed by tzdb have long been tab/space-agnostic,
so our general response is that parsers should be, too.

--
Tim Parenti
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mm.icann.org/pipermail/tz/attachments/20240207/4d390aab/attachment.htm>