Re: [Doxygen-users] Is doxygen.css restricted by GPL?

[Dimitri v. H. <do...@gm...>]

Hi Alan,

> On 15 Jun 2015, at 16:10 , Alan Brogan <Ala...@s3...> wrote:
> 
> Hello the list,Send
> 
> I am scanning commercial source code to ensure that it complies with Open Source licenses. In doing so I have come across a file derived from doxygen.css in what is obviously a directory of documents produced by Doxygen. From the Doxygen overview (http://www.stack.nl/~dimitri/doxygen/manual/index.html) I notice that "Documents produced by doxygen are derivative works derived from the input used in their production; they are not affected by this license".
> 
> It looks like the intention there is that the "documents" are not subject to the GPL, and it applies in a straightforward way to documents primarily derived from "our sources". However the wording becomes problematic when I try to apply it to a file derived from doxygen.css as I can see a number of interpretations which would lead to opposite conclusions:
> 
>     1. *.css are not "Documents" (they're support files), so the exception is void and GPL applies
>     2. The file I found is derived from doxygen.css which is part of the Doxygen project, hence subject to GPL, and that license "carries through" to the output version, so GPL applies.
>     3. The intended effect of this exemption is to allow "the output docs" to be distributed without GPL. The file I found is part of "the output docs", so GPL does not apply
>     4. The file I found is derived from Doxygen, but this exemption removes it from Doxygen's general GPL licensing. In other words: doxygen.css is subject to GPL while part of the Doxygen source, but not subject to it once placed in the output directory. So GPL does not apply.
> 
> So: does the modified doxygen.css have to be distributed under the GPL?

My intention is that doxygen.css is to be considered part of the documentation (so 3 and 4 apply). 

If you want to play really really safe (shouldn't be needed but I'm not a lawyer), 
you can also define a custom style sheet that overrules only the parts doxygen.css that need modification
and use HTML_EXTRA_STYLESHEET to make that delta style sheet part of the documentation set. That way you don't modify doxygen.css and still have
the same end result. An additional benefit is that you are less sensitive to future changes in the stylesheet.

Regards,
  Dimitri