License.txt

  Pinball source code
  ~~~~~~~~~~~~~~~~~
  License for use and distribution
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  Pinball Copyright (C) 2000-2016 by Henrik Enqvist

  Licenses for files are:

    1) Core license is GPLv2+
    2) gnu table licenses are (GFDL or Free Art or CC-BY-SA) and GPLv3 and
    CC-BY-SA (data/gnu/README)
    3) hurd table license is GPLv2+ (data/hurd/README.txt)
    4) professor table license is GPLv2+ (data/professor2/README.txt)

  Full package could be License as GPLv2+ and (GFDL or Free Art or CC-BY-SA) and GPLv3 and CC-BY-SA

We have a review here: https://bugzilla.redhat.com/show_bug.cgi?id=1290935 if
something is not correct please let us know to fix it..


References:
https://github.com/sergiomb2/pinball/pull/3#commitcomment-20063738

The core license is GPLv2+, not GPL+.
I have released hurd and professor2 on the same license on purpose to avoid creating problems with versions of the GPL.

The gnu table can create problem with a next release of GPL (a hypothetical GPLv4).

however, the full package including gnu must be released under GPLv3.
Or gnu should be kept separate.

It would be a good idea to contact Ben Asselstine for verify if it's possible to port gnu on GPLv3+.
So the entire project can be GPLv3+.

in fact also https://sourceforge.net/projects/pinball/ says License: GNU General Public License version 2.0 (GPLv2)