[tz] Preparing to fork tzdb

[Guy Harris]

On Sep 20, 2021, at 7:57 PM, dpatte via tz <tz at iana.org> wrote:

> When I read an astronomical journal and read of a bolide sighting in 1957 at 7:30 PM in haiti, it is important that I can attach that to a ut in 1957. But if it's now in the 'merged data' I am now out of luck.

As long as it's well established that Haiti didn't observe DST in 1957, as the current northamerica file claims is the case, that works.

If it's not, well....

(I.e., how "reliable" data for a given tzdb region and a given time in the past is probably depends on how far back in the past it is and how well offset and time-shifting rule changes are documented - and what sources people have checked.)