[tz] Use or Apply for SPDX Licence

[Russ Allbery]

"Artemis Tosini" <me at artem.ist> writes:

> In many countries it is not possible (or is unclear if it is possible)
> to put a work into the public domain and grant all rights. Some
> licenses, such as CC0, are designed so that even if putting works into
> the public domain is invalid users will still have all rights afforded
> as if it were in the public domain.

However, given that all of the people who have historically submitted
commentary or other patches that have been incorporated into tz did not
agree to the CC0 license explicitly or implicitly (the license postdates
much of this work), it's hard to see how anyone could reasonably claim
that tz is under such a license.

There is a large grey-area assumption with most free software packages
that do not do either copyright assignment or CLAs that people
contributing patches are doing so under the prevailing license of the
thing to which they're contributing at the time and cannot reasonably
object to their work being redistributed under that license.  That license
for tz has been stated for some time to be "public domain" and prior to
that was left largely unstated.  Despite all the issues with the "public
domain" concept in international copyright law, I doubt claiming some
other license now would be on any firmer legal ground.

The practical reality is that it's highly unlikely that anyone is going to
assert copyright rights over material in the tz distribution (to the
extent that it's copyrightable at all, which is probably limited to the
code and the commentary), and if they do, the details of the case seem
likely to turn on elements other than the license statement.

Lawyers may not be happy about the uncertainty and may want to transfer
that uncertainty to some other party with some legal document.  If I were
Paul, I wouldn't want any part in that.  There's essentially no upside for
him as maintainer to accept any responsibility or liability for the
uncertainty.  If IANA wants to take on some of the legal uncertainty,
well, at least have legal counsel to advise on the merits of and tactics
for doing so.

-- 
Russ Allbery (eagle at eyrie.org)             <https://www.eyrie.org/~eagle/>