[tz] Version in zoneinfo files?

[Brian Inglis]

On 2015-10-28 02:12, Paul Eggert wrote:
> lester at lsces.co.uk wrote:
>> The version number is essential data
>
> It's not essential to put the version number into zic's output, as the tz project has been operating successfully for decades without doing so. Although there are benefits to having a version number in the data, there are costs too, and it's not clear which is greater.
> If one needs a unique number to briefly identify a data file, one can use a hash function of the data. This should suffice for tzdist's needs, so that tzdist shouldn't require a version number in the data.

Seems essential to document the provenance of the data using the kind of output --version produces from some packages, which include explicit build libraries and versions, e.g.
2015g+zone1970.tab
where zone.tab could replace zone1970.tab; +backzone, and +(NIST)leap-seconds.3629404800 could be added, with (IERS) a (singular but possibly more secure and authoritative) alternative to (NIST); and local commit hash added like +https://github.com/eggert/tz/commit/6bf2f29c6458f8aa245dd5780235a38e6142bbef.

[Last time I checked, only 9 of 24 NIST servers, and 2 of 9 nist.gov servers {time,wwv} offered anonymous FTP leap seconds files.]

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada