[tz] Preparing to fork tzdb

[Paul Eggert]

On 9/20/21 2:58 PM, Robert Elz wrote:
> If someone in (or from) Angola or Niger wants th research their timezone
> history, and send it, it should be included, just like that for the US,

Yes, and there's a place for that in 'backzone'. We're not refusing 
timezone history because it's unnecessary due to the alike-since-1970 
rule. It's put into 'backzone' and is welcome there.

Perhaps some people have the misimpression that we have many potential 
contributors whose data are being refused. On the contrary, almost 
nobody contributes historical data, because it's boring unpaid work and 
honestly, it's not that important. I know that, because I contributed 
the vast majority of 'backzone' (a contribution that I'm coming more and 
more to regret :-).

This disagreement is not about whether the data in question are 
available; it's only about which file they're in. Nothing is being 
"wiped out" or refused.

> I've always believed that there should be at least one zone for
> every time zone authority on the planet

That would be ideal, and I hope something like that would be doable for 
current and future timestamps. But it'd be a stretch to try to do it for 
all timestamps since 1970, and it'd be completely impractical for 
pre-1970 timestamps. We don't know who the historical time zone 
authorities were, much less what rules they used.

> The only real cost is a little extra processing time generating the zones,
> and a trivial amount of zone data files.

I think this greatly underestimate the effort to do a complete job. We'd 
eventually need thousands of Zones. I expect we'd have to revamp the 
underlying technology too, and do something more like what Shanks 
evidently did (though I haven't seen his source code). I would not 
consider that trivial, and I think our collective effort would be better 
spent elsewhere.