[josm-dev] License clarification for JOSM plugins

[Gervase Markham]

(Full disclosure: I do licensing for the Mozilla Foundation, so have 
some familiarity with this topic.)

Lauri Hahne wrote:
> I'm not a developer of JOSM but I think you're on very thin ice trying
> to distribute JOSM under GPL3 or later. This is because currently most
> (if not all) source files tell that the license is just GPL which is
> very vague. 

The ice is not nearly as thin as you think.

"If the Program does not specify a version number of the GNU General 
Public License, you may choose any version ever published by the Free 
Software Foundation."
(GPLv3, section 14; GPLv2 section 9; GPLv1 section 7)

> In addition, the LICENSE file only has GPL2. 

Here we need to distinguish between the licence text, as found in the 
LICENSE file, and a statement that the licence applies to some 
particular code, which is normally found at the head of each file. JOSM 
has the former, but does not have even a single file containing the 
latter, at least not in the "core" directory. (Some of the plugins are 
better in this regard; I haven't looked at them for the purposes of this 
email.)

Without a specific statement of applicability, I think it can be implied 
that JOSM is under the GPL, but as no version number has been given, any 
version can be used. You might suggest that the placing of the version 2 
text in the LICENSE file might imply version 2 only, but I don't think 
it does. If it did, how would one indicate the opposite - that any 
version is permissible? After all, one can hardly put the text of every 
version, both existing and yet to be written, in the file.

There's an entire section on "How to apply these terms to your new 
program" in the GPL, version 2 at least. Perhaps the JOSM maintainers 
should consider following it. Then their intentions would be more clear.

I would suggest that the developers should not attempt to stop people 
using the software or parts of it under later versions of the GPL 
without a clearly articulated reason.

Gerv