On 10/25/20 10:45 AM, Kristin Minchev wrote:
The [leap-seconds.list] file itself doesn't have any license information (nor NIST's).
Under current US law a file that contains no license information normally defaults to being copyrighted with no license granted. The NIST is an arm of the US government, though, so under US law its publications are public domain so we don't have to worry about redistributing the NIST file even though it contains no license info. I just now searched for the top ten "leap-seconds.list" hits on Google. The #1, #3, #4, #6, #7 and #9 hits were about the NIST file, and of these all but #9 were about the tzdb copy of the NIST file (#9 was unclear). The #5 and #10 hits were about the IERS file. (#2 and #8 were false matches.) So even though the IERS file is published by the primary source for leap seconds, licensing issues have prevented the IERS file from being the most popular in practice. We've attempted to contact the IERS multiple times to get its file's license clarified, but haven't made much progress.
And most of the data comes from IERS anyway.
That's fine: under US law, data cannot be copyrighted. There was a court case about this; see <https://www.eff.org/press/releases/eff-wins-protection-time-zone-database>. I installed the attached patch to the tzdb development repository to try to explain this all a bit better, without getting too long-winded about it.