[tz] error Portugal 1980

[Tim Parenti]

On Thu, 29 Feb 2024 at 06:31, Alois Treindl via tz <tz at iana.org> wrote:

> I think there is an error in TZ, regarding begin of DST in Portugal in
> 1980.
>
Some time ago, I'd looked into some other changes for Portugal and found
that our data there, which is mostly from Shanks, likely needs a
complete overhaul, much like I did for Uruguay in 2018
<https://mm.icann.org/pipermail/tz/2018-February/017706.html>.  I'd made
significant progress on this, working on data from Observatório Astronómico
de Lisboa, before more important things came up and I had to shelve the
branch.

I just checked, and it seems I'd ended up with "Apr Sun>=1 1:00s" for 1980,
which is equivalent to the law text you provided (at least for the
mainland, "1 hora de tempo universal"), but not quite to your patch.  But,
for example, I'd also had that for 1978 and 1979 as well, which is an hour
different to what's currently in tzdb for those years.

If you'll allow me a few days to dust off and clean up what I had already
for the mainland, I'd rather we take the time to ensure this is done right
and not commit changes here in a piecemeal fashion.  I imagine there might
be a couple revisions before it ultimately lands in the repo, but as this
is all historical there is no urgency.

One thing I *know* I could use help with, and that we need to be careful
of, is figuring out how changes to 'Port' rules, in use until 1983, affect
Azores and Madeira.  Since we seem to know that Portugal didn't harmonize
with EU DST practice until 1992, I wouldn't want to guess that that's what
was done 1916–1983.  So if someone could help find *some* relevant text
from that period, that would really help.

https://diariodarepublica.pt/

--
Tim Parenti
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