Date: Thu, 23 Sep 2021 07:49:31 +0200 From: Eliot Lear via tz <tz@iana.org> Message-ID: <1949110b-0201-63a3-bb7f-728bc868a7f0@lear.ch> | Unless of course if the data moved is questionable of questionable origin. The data may have 3 different (perhaps more if one cared enough) trust levels... 1. It can be backed by verifiable sources that seem to be reliable, so we believe it. 2. It is disputed by verifiable sources, that seem to be reliable, so we consider it incorrect. 3. Neither of those, and we simply have no way to know. In that, no-one questions use of type 1 data, and type 2 simply becomes type 1 after the obvious correction is made. The disputes are all about #3 - and certainly you can call that questionable, or arguable, or various other similar terms - none of which actually mean anything. Everything can be questioned, and so is questionable. What the time currently is, right now, in London can be questioned, so that is questionable. Should that data be removed from tzdb because of that? If you want to claim some data is incorrect, provide evidence to support that, otherwise you're simply maligning whoever supplied the data in the first place (nb: not necessarily the person who edited it into tzdb, but the source of their information.) For any data to be in tzdb, at some time or other, someone believed it might have been correct (no-one has ever, typos excepted, deliberately added bogus data) - their belief might have been incorrect, but to remove that data, just wondering "was that correct" should not be enough - we should need #2 type evidence - something that shows that some entry is actually wrong. That has happened often enough that we know corrections get made when needed. Simply discarding data because we neither ever had (or perhaps simply did not record, perhaps because it was not provided to us) the evidence to support some apparent claim is not a sane way forward. And it is even worse when the effect of this is to (effectively) remove the old data (anything present in backzone is effectively removed, even though it is still there in the file, as no-one uses it). Eg: to re-use an example that has been used here a bit recently, if someone today looks at the app which translates dates & times of historic events to the local time of the requestor ("what time was it, for me, when Armstrong stepped onto the moon's surface?" etc). If someone in Montreal did that, and got what they believe was the wrong answer (because they remember the event), then investigate why, and see "We use the data for Toronto, and that answer was correct for Toronto" they'd perhaps wonder why, but that would be the end of it. But if they were instead using the data for Montreal, and it turned out to be incorrect, they'd actually complain (probably to the authors of the app, who would then complain here). That way the data might be corrected. But not if it is buried in backzone. kre