This is an outrageous attack against a case of perfectly legal use of published data.
Where tzdata has used information from ACS atlas, it quotes it source (Thomas Shanks, former employee of ACS Inc, San Diego, who appears as author on the printed books American Atlas and International Atlas).
In each case, the information published by Shanks was critically reviewed by the tzdata community. In many cases, Shanks' information was rejected, in many cases it was accepted over other contradicting (or confirming) information.
Shanks did not create the information in his published books, he collected it from other published sources, though the books fail to name the source of the information in nearly all case.
Relevant sources of Shanks, especially for International atlas, were
- Gabriel, Traite de l'heure dans le Monde, Paris
- Henri Le Corre, Regimes Horaires pour l'Eruope et l'Afrique
- Doris Chase Doane, Time changes in the world
- Doris Chase Doane, Time changes in the USA
- Curran and Taylor, World daylight saving time, Chicago 1935
many other publications appearing in the astrology domain.
The two books by Shanks consist to 95% of lists of towns with longitude and latitude, their assignment to counties or provinces, and their assignment to timezone
history tables. tzdata uses NOTHING of this information, as tzdata does not contain assignments of towns to zones, except the single town in each zone used for naming it.
Shanks has about 2000 of different timezone history tables, they make up about 5% of the books volume.
tzdata has only about 400 different timezone history tables, because tzdata is historically not complete. It is only complete for the post 1970 era (where ACS is incomplete, and where ACS newer editions have used a lot of data taken from tzdata. Legitmately without quoting the source, as tzdata is public domain.)
Tzdata quotes Shanks for about 100 of these tables (I gues, I did not count), as one of the sources of historical timezone information.
In each case, the data given of Shanks were critically reviewed.
A perfectly legitimate use of published data.
The information about which time public clocks showed at a particular date in a particular country or region is by its very nature public information. It is not subject to copyright. Shanks does not own it, he has only collected it, and he is as often false as other collectors are sometimes false.
The use tzdata makes of such information is fully legitimate. It did by no means copy data from these books. It critically reviewed some of the information found there, and used a small amount (maybe 1% of the book content) in a completely different context and different representation.
The attempt by Astrolabe to claim private rights on public domain data must be forcefully resisted by the tzdata community.
I would hope that large users of tzdata, like Apple (in IOS and MAC OS-X), Redhat and other Linux distributors etc will contribute to a defense fund for Olson, and/or contribute legal assistance.
Plus: Astrolabe has very little money