[tz] [PATCH 2/3] Replace some zones with links when that doesn't lose non-LMT info.

Paul Eggert eggert at cs.ucla.edu
Wed Sep 4 18:01:24 UTC 2013

On 09/04/13 09:24, Stephen Colebourne wrote:

> If Scotland has its own time different
> from England, then one tzdb might name it Edinburgh and the forked
> tzdb uses Glasgow. That divergence, or non-ubiquity, would be very
> unhelpful to everyone that needs time-zone data.

Yes, we should try to avoid this.  Nothing like that is
being proposed, thanks goodness.

> For example, the removal of "Castries Mean Time" and "Kingstown Mean
> Time" will be visible in Joda-Time, and the change to the end of LMT
> will be visible in Joda-Time and JSR-310.

No historical data are being lost here.  "Castries Mean
Time" and "Kingstown Mean Time" are artifices of the tz
database (I should know, since I invented them) and do not
reflect any known historical data.

More generally, no doubt regression tests will report
changes because of the proposed patch, because that's what
regression tests do: they report changes.  But ordinary
users won't care that time stamps in Aruba on February 12,
1912 from 04:35:47 to 04:40:24 UTC will have a UTC offset
that differs by a few minutes.  They just won't.  We've done
this sort of thing before, and it doesn't cause problems.
The tz database has often seen updates like this, and it's
just not that big a deal.

> America/Curacao and America/Aruba have exactly the same
> time since the year dot apart from the LMT value (they do have the
> same LMT end date).

The transitions don't have the same UTC end time, though, so
merging these two would also cause regression software to
report a change.  If "no change" is the criterion, then no
changes will pass muster.

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