[tz] attic data for the tz database

[Paul Eggert]

Stephen Colebourne wrote:
> On 29 August 2013 21:18, Paul Eggert <eggert at cs.ucla.edu> wrote:
>> As we've seen, similar changes have been made to the tz database
>> regularly, and evidently those users didn't notice or care.  What's
>> different about these changes?
>
> Firstly, there are a lot of recent changes.

Sure, but there were more changes in the past, and they
didn't cause problems.

> Secondly, some of them are more political than in the past, notably
> cross border.

Sorry, but that's incorrect.  The past changes were
cross-border and were more political than the current
proposal.  For example, a year after the Siege of Sarajevo
(the longest siege of a capital city in the history of
modern warfare, and the focus of an intensely bitter Balkan
war), we merged Sarajevo with Belgrade, on the grounds that
their post-1970 time stamps were identical.  Nobody noticed
or cared.  Nothing in the current proposal is remotely close
to that merger, in terms of political controversy.

So our practical experience suggests that the proposed
changes won't cause any real problems.

> Add a "historical data
> reliability" indicator to each zone. Say, the earliest date from which
> the data is regarded as being acceptably reliable.

I'm afraid that sounds like a lot of work, and it's not
something that can be reliably determined -- at least, not
unless we arbitrarily put in "1970" for a large majority
of entries, and then what's the point?

> I'm not that interested in resurrecting long dead data

OK, in that case we can make the attic smaller, and use it
more on a going-forward basis, with 2003d as the starting point.
This will be a smaller change to the database now, which I
assume is a good thing.