Subject: [Stratego-dev] license and copyright faq
From: Martin Bravenboer <[email-masked]>
To: [email-masked]
Date: Sun, 03 Aug 2003 16:03:24 +0200

Hey,

I think there should be some items in the FAQ on license and copyright 
issues. Although I'm not a lawyer, I've tried to answer the most obvious 
and important questions. I would like to know whether you agree with my 
answers before I put them on the Wiki.

There is one important issue on importing Stratego modules. Please read 
this section. I think the grant I propose there is necessary if we want 
the switch to the LGPL license to be effective. I think free software 
guys will not like the additional grant, but well ...

I wanted to keep the answers clear and short, but unfortunately it 
became quite a story. License issues are boring.

Cheers,
Martin

---+ License and copyright

---++ Can I use StrategoXT in non-free software?

Yes you can: from [[StrategoRelease09][release 0.9]], StrategoXT is 
licensed under the LGPL. Because of this you are allowed to use any 
license for "work that uses <nop>StrategoXT".

However, if you modify the sources of <nop>StrategoXT (aka work based on 
<nop>StrategoXT), you must distribute the sources if you are 
distributing the modified work. In other words: only changes to 
StrategoXT itself have to be made public.

More information:
    * [[http://www.gnu.org/licenses/lgpl.html][LGPL license]]
    * [[http://www.gnu.org/licenses/gpl-faq.html][GNU GPL FAQ]]

---++ Is an import of a Stratego module dynamic linking?

Firt of all we should explain why this is an important question. The 
LGPL states that creating an executable that contains portions of an 
LGPL library (aka *static linking*) creates a derivative of the library. 
In this case someone should be able to re-link your object files with a 
modified library. Distributing your executables without the *object* 
files of your own program and sources of the LGPL covered library is not 
allowed. If you are using *shared libraries*, there is no problem 
because you are not distributing derivatives that contain portions of 
the library.

Stratego does however not support separate compilation, thus it is not 
possible to compile Stratego modules to shared libraries. All executable 
Stratego programs contain portions of the modules they are importing.

Because of this limitation of the current compilation scheme and to 
allow the distribution of executables that import Stratego modules 
covered by the LGPL, we explicitly grant you the right to import a 
Stratego module part of StrategoXT, without having to distribute your 
object files and the sources of the Stratego modules being used.

Note that if Stratego supports [[separate compilation]] in the future, 
this additional grant will not be necessary anymore because the Stratego 
module can then be compiled to a shared library.

Invoking an executable tool with XTC is not a problem because your 
executable doesn't contain portions of the tool you are invoking.

---++ Why does Eelco Visser own the copyright of all sources of StrategoXT?

If you contribute a package, library or tool to the StrategoXT 
distribution you should assign the copyright to [[Eelco Visser]] (aka 
the Stratego Software Foundation ;) ). Make sure that your employer is 
ok with this, because often your employer is the copyright holder of the 
software you produce in the scope of your employment.

Eelco Visser as the only copyright holder has the right to change the 
license of StrategoXT in the future without asking every single 
contributor (copyright holder) whether they agree with the license 
change or not.

This issue came up when the license of StrategoXT changed from GPL to 
LGPL. We decided to change the license to allow the application of 
StrategoXT in non-free software.

More information on copyright:
    * [[http://www.wikipedia.org/wiki/Copyright][Wikipedia]]

---++ But I want to include myself in the list of authors!

That's ok. Mentioning that you've written a piece of software does not 
imply that you are the copyright holder, although normally an author 
will claim the copyright and in the US the author holds the copyright of 
his work even if there is not copyright notice. Although we ask you to 
assign the copyright to Eelco Visser, you can still include an informal 
statement that you've written a piece of software.

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