Paul Eggert via tz said:
On 10/18/21 06:07, Stephen Colebourne via tz wrote:
What tzdb previously offered was a set of IDs, based on a simple rule - "ID as needed for post-1970 data, with at least one per ISO country".
But there's an even simpler rule: "ID as needed for post-1970 data".
Full history was available for each of these (whether accurate or not).
That wasn't ever the case. For example, there was never full history (accurate or not) for San Marino. We shouldn't base our analysis on the idea that we formerly had at least one Zone per ISO country, as we never had an ironclad rule like that and we did just fine without any such rule. There's no *timekeeping* reason to require a Zone for every ISO country.
I agree with this.
Adding such a requirement would complicate maintenance. It would add a significant amount of likely-bogus data, as witness the recent discussion about the likely-bogus data for Bamako that's in 'backzone'. And it would increase the role of politics particularly as new countries emerge, and politics is something we should avoid as much as possible.
Suppose that a new "country" (quotes because not all ISO 3166-1 entries are countries and I *REALLY* don't want to start arguing which ones are) is formed. We now have to split a zone into two with identical post-1970 data. But what do we use for the pre-1970 data? One of them will have to take data for a city in a different country. Precisely what Stephen has been arguing against! We need to decide what TZDB's policies are in relation to pre-1970 data, including when and where the data is included, how to indicate the reliability of the data, and how to handle zone splits and merges.
What I am sensing from your proposal, as well as from some of the followup comments, is a need to further clarify exactly what the tzdb project's interfaces are.
I agree with this. I think it should have priority over the rest of this discussion. -- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646