[tz] [PATCH 3/3] * europe (Europe/Vaduz): Now a link to Europe/Zurich.

[Russ Allbery]

David Patte ₯ <dpatte at relativedata.com> writes:

> I actually don't use the LMT value in tz, so I am not personally
> concerned if it is lost, but I do use the date and time that the city
> moved from LMT, which would be a shame to lose.

The time of switch to standardized time was already identical between
Europe/Vaduz and Europe/Zurich.  However, now that I've looked at this
more closely, there is another (earlier) transition that may possibly be
of issue for data completionists, which is a new consideration that people
have only recently asked the database take into account.

Let me help for the people who don't have a copy of the current data
readily available.  Current (well, 2013d) Europe/Vaduz:

Zone    Europe/Vaduz    0:38:04 -       LMT     1894 Jun
                        1:00    -       CET     1981
                        1:00    EU      CE%sT

Europe/Zurich:

Zone    Europe/Zurich   0:34:08 -       LMT     1848 Sep 12
                        0:29:44 -       BMT     1894 Jun # Bern Mean Time
                        1:00    Swiss   CE%sT   1981
                        1:00    EU      CE%sT

So the result of this change for Europe/Vaduz is that the DST corrections
for Europe/Zurich from 1941 to 1942 would be adopted (which as Paul notes
is more likely to be correct than the previous state), the historic LMT
offset would change by an irrelevant four seconds, and the times between
1848 and 1894 would track Berne instead of Vaduz/Zurich LMT.

All of these changes are either more likely to be accurate than what we
had or are trivial to the point of irrelevance except for the last, which
does mean a change in abbreviation (LMT -> BMT) between 1848 and 1894, if
I'm reading the rules correctly, and a time difference of a somewhat more
significant 8 minutes and 20 seconds.

In terms of the current scope of the project, there is no reason not to
make this a link.  In terms of the desire to expand the scope project to
keep every piece of historical data as accurate as possible, I think
there's some question about the LMT to BMT change.  The question is
whether Liechtenstein would have done something other than all of
Switzerland during that time period (with the exception, noted in comments
but not in rules due to being out of scope historically for the database,
of Cantone Geneve, which kept LMT rather than Berne Mean Time from 1848 to
1894).

I am about as far from an expert in European history as one can possibly
get, so I don't know the answer to that question.  Wikipedia seems to
imply that Liechtenstein was closely aligned with Austria-Hungary up until
World War I, whereas Switzerland was an independent state, which makes me
a bit dubious that Liechtenstein would have standardized on Berne Mean
Time.

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>