[LEAPSECS] content of the NTP-aimed leap-seconds.list files

[Steve Allen]

The IANA tzdata now gets the complete leap second history
information from the file leap-seconds.list that NIST
has been publishing for the sake of NTP.

The NIST version of that file can be found at
ftp://time.nist.gov/pub/leap-seconds.list
(at least when the server is running, which I have found is not all
the time).  There are multiple older versions of that file with
timestamp integers in place of the "list".

The USNO has also been providing a version of leap-seconds.list at
ftp://tycho.usno.navy.mil/pub/ntp/leap-seconds.list
again with older versions named using a timestamp on the end.s

The IERS Paris bureau is also providing such a file.  That makes at
least three separate sources for this information.  Each source has a
different timestamp, a different expiration date, and different
commentary text.

All three versions include a SHA checksum that can be used to detect
unintentional corruption during data transfer, but that is not a
digital signature that can be used to detect intentional corruption.

This particular format of file has been deemed acceptable as input to
NTP daemons, for IANA tzdata, and in the experimental servers of the
IETF tzdist protocol.  Comparing these with the DNS mechanisms being
developed on LEAPSECS leads me to wonder ...

Are there other features which would be desirable as part of a file
intended to robustly communicate the full known history of leap
seconds?

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