About 10 years ago I created a startup that used the ACS database. ACS used to stand for Astro Computing Services and they used to publish ephemera as well as several publications which allowed you to lookup timezone information. This is a fairly extensive set of data if you want to translate local time at a particular time in the past (say, someone's time of birth as recorded on a birth certificate) into UTC time. Time zones have changed, time change rules have changed (for example, double summer time was observed in England during WWII) and one of the books I used to have from ACS (published back in the 1980s) claimed that this information had been compiled from a wide variety of historical records. One possible scenario is that Olson had written permission to use some parts of the data but a troll has purchased the copyright and is trying to profit from it and pretending they don't know nothin' about no permission. That would be a crying shame since putting the data in such a compressed form that is used on countless *nix servers and devices was an immense task - the original database was an ugly conglomeration of flat files that needed quite a bit of spanking to get it into a useable format, and was certainly not within orders of magnitude of the compactness of the Olson database. Anyway, on the surface, if this is the same ACS database there is quite a lot of data involved, much of it covering historical edge conditions, but I haven't checked to see how many of the edge conditions prior to 1970 are reproduced in the Olson database. From what little I know of the way these things work, the plaintiff would have to show that there was willful infringement without permission and that some damages occurred, but there would not be any value in the ACS data unless you needed to know with great reliability whether daylight savings time was in effect, say, in some rural county in Indiana at 4:06 am on 21 October 1947 (and for that matter, what was the timezone).