Copyleft, -or-later, and Basics of Compatibility

Free as in Freedom episode 0x09

February 15, 2011

Bradley and Karen discuss types of copyleft generally and introduce the basics of license compatibility and -or-later clauses.

Running time: 00:41:57.

This show discusses copyleft and basic issues of license compatibility (04:09)
Karen mentioned an episode of the old Software Freedom Law Show, Episode 0x08, where Bradley and Karen discussed selecting a FLOSS license and what the various options are. (04:45)
license compatibility 06:28
Bradley incorrectly said that the original Emacs license didn't have the word General in it. However, the other explanations appear to be correct. There's a useful history page that someone wrote about the history of GPL. It appears the non-general GNU copylefts existed from 1984-1988. (06:57)
Karen noted that the Library GPL was renamed to the Lesser GPL which happened in 1999. (09:30)
Bradley mentioned that when he and RMS worked on the GNU Classpath Exception, Bradley suggested it be called the Least GPL. (10:38)
GPL doesn't have a choice of law clause. If a another copyleft does, it surely is incompatible with the GPL. (14:17)
AGPLv3 § 13 and GPLv3 § 13 explicitly make themselves compatibility with each other, which Bradley calls compatibility by fiat. (15:40)
Karen mentioned that the Mozilla Public License § 13 has a section about multiple licensed code (16:50).
Bradley mentioned that Mozilla Firefox uses a combinatorial license: (GPL|LGPL|MPL), which is a disjunctive tri-license. (19:00).

Bradley mentioned that the old Software Freedom Law Show Episode 0x17 discussed compatibility of permissively licensed software and copylefted software. (20:22 )
Apache Software License 2.0 was likely the first FLOSS license to have an explicit patent licensing provision (23:40)
Bradley and Karen discussed the fact that -only vs. -or-later are options with the GPL, while they are not with other copylefts, such as CC-By-SA. (30:11)

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