I contribute from the standpoint of a developer and maintainer of astrology software and astrological web services.

Astrologers need pre-1970 data for correct astrological charts.

I accept that it is the responsibility of the 'astrological community' to collect and maintain historical time zone information. Thomas Shanks has been an important researcher in this field, and his data were published in book format. Some people I do not need to mention now made wrong business decisions by trying to make these data their private intellectual property, but these attempts have successfully challenged and were rejected.

We can collectively consider time zone history information published in books as free public domain data.

Of course I vote for the continued maintenance of pre-1970 data in TZDB.

Among Stephen Colebourne's proposals, I think 2) makes the most sense.

2) Pre-1970 data for each ID meeting the rule "ID as needed for
post-1970 data, with at least one per ISO country"

Considering all the existing Link records and backzone data, the condition 'at least one ID zone per ISO-country' is mostly fulfilled. If here is something missing, it can be added over a period of time without any urgency.

Thanks Brian and Adhemar for your thoughts. Does anyone else want to
chime in on the best way to move forward?
thanks
Stephen


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