[tz] Single source of truth for timezone data

[Robert Elz]

Also copyrights notwithstanding (but still mportant), considering that
metaZones.tzt file that Paul included in the message to which I am replying,
as a "source of truth" is laughable.

tzdata isn't perfect, though it (at least until a couple of years
ago) always strived to have the best known data available to us.

That file contains nonsense:

        "Australia:Brisbane"{
            {
                "Australia_Eastern",
            }
        }
        "Australia:Sydney"{
            {
                "Australia_Eastern",
            }
        }

That cannot be right, the times in Brisbane and Sydney (right now)
aren't the same - they cannot possibly (whatever the rest of that
data actually means) be treated the same.   We also see:

        "Australia:Hobart"{
            {
                "Australia_Eastern",
            }
        }

which is less bad right now, as Hobart's and Sydney's clocks, today,
are the same - but they haven't always been, not even back to 1970.

The same issue applies to:

        "Australia:Adelaide"{
            {
                "Australia_Central",
            }
        }
        "Australia:Darwin"{
            {
                "Australia_Central",
            }
        }

The clocks in Darwin and Adelaide (right now) are not the same either.

I haven't checked all of the rest of it, but if just this sample is
this bad, why would anyone want to even consider distributing this stuff?

Note that the next version of POSIX has extended its definition of TZ
(or will have, after it is completed, approved, and published)
in a way that allows both America/New_York and Australia:Adelaide
(and many other possibilities) to be valid TZ strings (it still allows
leading ':' strings for implementation defined specifiers) - but it
requires that such timezones contain accurate zone data for all transitions
since the epoch (1970-01-01T:00:00:00Z) and encourages providing the best
possible data for older times.    That is, implementations must map
Australia:Darwin into Australia/Darwin if using tzdata, not to
Australia/Adelaide, and similarly Australia/Sydney Australia/Brisbane and
Australia/Hobart must refer to 3 different transition lists.

kre