[tz] Historical discrepancies for Italy.

Pierpaolo Bernardi olopierpa at gmail.com
Fri Oct 21 22:33:19 UTC 2016

On Fri, Oct 21, 2016 at 10:31 PM, Brian Inglis
<Brian.Inglis at systematicsw.ab.ca> wrote:
> On 2016-10-20 15:27, Pierpaolo Bernardi wrote:
>> about Italian time, I see:
>> # From Paul Eggert (2006-03-22):
>> # For Italian DST we have three sources: Shanks & Pottenger, Whitman, and
>> # F. Pollastri
>> # Day-light Saving Time in Italy (2006-02-03)
>> # http://toi.iriti.cnr.it/uk/ienitlt.html
>> # ('FP' below), taken from an Italian National Electrotechnical Institute
>> # publication. When the three sources disagree, guess who's right, as
>> follows:
>> I don't know about the other sources, but:
>> - the url given to cnr.it is dead.
>> - The authoritative source for time in Italy is the national
>> metrological institute, which has a summary page of historical DST
>> data at http://www.inrim.it/res/tf/ora_legale_i.shtml
>> - Some of the data in TZ does not agree with this page.
>> I think that there must be VERY strong evidence that the INRIM is
>> wrong before preferring other sources?
> Hi Pierpaolo,
> That page does not cite any of its sources:

They are the National Metrological Institute, they are the source of
time, both for scientific and legal purposes in Italy.

> - some of them could be those used in the tzdb or the tzdb itself;

I doubt that they need any external reference for these matters. They
are the ones who are actually implementing the switches since 1934.

> - tzdb prefers official government sources as references, better if viewable
>   online;

This is exactly what they are.  You can't get any more official
government source than them.

> - perhaps you could contact INRIM to find out if they can provide references
>   to information of which the list was not previously aware?

Doesn't make much sense to ask them for their source, as they are the
ones which tell Italy what time it is.
There's nothing more authoritative they could appeal to for support
(nowadays they participate in the realization of TAI, and realize
UTC(IT) and disseminate it through Italy. See
http://rime.inrim.it/labtf/ ).

The Institute exists and operates in this role since 1934 as Istituto
Elettrotecnico Nazionale Galileo Ferraris first, then renamed Istituto
Nazionale di Ricerca Metrologica in 2006.

Anyway, if you can suggest a precise question to ask, I'll ask (and
I'm sure they can also reply in English to an enquiry in English. The
email given for external relations is press at inrim.it).

I anticipate that  their reply will be: this is what we have in our records  :^)

> Also perhaps you (or they) could say what the phrases:
> "dalle ore X del" and "alle ore X estive del"
> mean in this context?

"Dalle ore X del" = from hh:mm of [day]   (can be inferred from
context that they mean local standard time)

"alle ore X estive" = to hh:mm summer time (local DST).

> I have attached comparisons of the data from the table on the web page,

Thank you. I'll study your comparison later. I didn't do a sistematic

> Some assumptions were made in the comparison:
> - web page times are local standard time for daylight start entries and
> local
>   daylight time for daylight end entries;

this is correct.


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