Derick Rethans via tz said:
2) Negative DST Negative DST in the source files continues to be a problem, but we should address other issues first.
When I first highlighted this Irish case (https://mm.icann.org/pipermail/tz/2017-December/025621.html), it was never my intention that the tz data was changed to negative DST - I was originally only pointing out that IST isn't only Iran Standard Time, but also Irish Standard Time. I don't mind how it is recorded, as long as it produces the right output (in the form of transitions).
If negative DST represents what actually happens in the real world, then that's what we should be using. If implementations can't cope with negative DST, then they have bugs in them and/or don't match the real world. They need to change; we should not be lying to everyone just because some people won't face reality. (I don't object to a mechanism for people to do a build with the lies in, provided they have to explicitly accept it. Lies shouldn't be the default.) The other thing I think we need to discuss in this debate is the intent of pre-1970 data. It should be clear to people what this data is meant to cover. I was under the impression that pre-1970 data represents the time in at least some part of the zone. So, at present, the Berlin zone has pre-1970 data that represents at least part of Germany and the Stockholm zone has pre-1970 data that represents at least part of Sweden. If these are merged, the resulting zone has two names but both only contain pre-1970 data for part of Germany. In this case, it needs to be made very clear that the area covered by Stockholm is "Germany and Sweden", not "Sweden". The problem appears, to me, to be two zones that have the same contents but different descriptions. That would need to be fixed. (Personally, I'd like all the pre-1970 data that we used to have to still be available. But I understand that Paul doesn't want to have to change dozens of zones that last differed in the 19th century just because of a change in the 21st. There ought to be a solution to this.) -- 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