[tz] Error in Scandinavian tz data

[Paul Eggert]

On 2023-06-27 04:09, Stephen Colebourne via tz wrote:

> 'make ZFLAGS=-r at 0' is of no interest to packagers precisely because it
> is obviously wrong.

Then I must not be understanding "the default IANA build should say 
nothing about dates before 1970-01-01", a proposal that you said was 
acceptable. I thought "make ZFLAGS=-r at 0" would implement that proposal, 
as it builds TZif files that say nothing about timestamps before 1970. 
But since you're saying "make ZFLAGS=-r at 0" is of no interest, it seems 
the proposal is about something else. If so, it would be helpful to know 
what the proposal is.


> Just returning UTC does not meet these goals.

"make ZFLAGS=-r at 0" does not cause tzdb localtime to just return UTC, as 
localtime also returns an error indication indicating that the actual 
offset is unknown. This error indication is in the form of the time zone 
abbreviation "-00".


> the data for Copenhagen is likely to be entirely correct

I doubt that, as some of the data are sourced only from Shanks, which 
has proven to be unreliable.


> there is also a need to recognise that TZDB's
> pre-1970 data is the de facto truth 

That would not be accurate advertising. TZDB is only TZDB. It has never 
been "the de facto truth", unless "truth" means only "act like TZDB 
Release X". For many years TZDB's files have said that it is "by no 
means authoritative", and for many years TZDB installations have varied 
in minor ways from one platform to another.