[tz] [PATCH] Revert recent pre-1970 changes.

[Paul Eggert]

Stephen Colebourne wrote:

> Currently, the zone.tab file has entries for places like Europe/Zagreb
> that point to the backward file. That is something I object to

Well, as I said, I view that as purely an internal
maintenance issue, but I can see your point of view as well.
Since there are evidently real concerns about this, and
since it doesn't matter that much from my point of view,
I'll propose moving those Link directives back to
'northamerica' and 'southamerica'.  This should be the next
proposed-patch email coming from me.

> I'm just about happy to accept Europe/Zagreb ->
> Europe/Belgrade (in the main files), thus I'm also just about happy to
> accept America/St_Thomas <--> America/Tortola (in the main files, and
> assuming there is no other data being lost)

OK, I'll propose a change along these lines as well.
That'll be in a followon patch email.

> Refactoring isn't helpful for stability and causes
> unecessary debates like this.

But this is more than refactoring: it's simplification.  It
lessens the number of TZ settings that users need to worry
about, which is a Good Thing.  It lessens our exposure to
future political hassles, also a Good Thing.  And it shrinks
the size of the binary tz data a bit, which is another
win.

> ISO-3166 ... is as much a part of the data here as the time-zone data.

Maybe a bit of history here would be helpful.  By design,
the time-zone data are primary, and the ISO 3166 data is
secondary.  Arthur David Olson designed the time-zone data
format originally.  I designed the zone.tab and iso3166.tab
formats as add-ons later, purely to help users choose TZ
values; those tables were deliberately designed to be
separable from the primary data, and the primary data can
easily be (and often are) used without them.