[License-discuss] Changes made by derivative works

[Ben Reser]

On Thu, Jan 31, 2013 at 9:48 PM, Prashant Shah <pshah.mumbai at gmail.com> wrote:
> On Thu, Jan 31, 2013 at 8:13 AM, Ben Reser <ben at reser.org> wrote:
> I didn't mention this previously but Apache license has a clause if
> the work is submitted back to inclusion it has to be under the same
> license.

Yes it does.  Which is why minor patches are accepted by the ASF without a CLA.

> If the distributor of the modified Works chooses a different license
> for his modifications then it is his/new license responsibility to
> take care of the book keeping clause.

No, the license doesn't matter.  If you redistribute a modified file,
regardless of how you chose to license your modifications you need to
specify that you modified the file.

In practice nobody marks modified files that they are contributing
back to the ASF.  I'd say there's some ambiguity in the license here
since technically you probably should.  However, I believe the intent
of the license is not to treat contributions as redistribution.

>> Resulting in the need to know if someone has modified the file for copyright purposes.
>
> Sorry I didnt quite understand this point.
>
> I feel quite lost now :( but learnt a lot of new things also in this process :)

Do realize that my statement is an opinion.  I wasn't involved in the
drafting of the license so I can't be definitive as to the intent of
the authors.  But I believe the purpose to be to identify modified
versions and to aide in the determination of their licensing.  See
further on down in the email for an example.

> Coming back to the original question that I had. I can now put it in a
> much better way...
>
> It is the responsibility of who is accepting/distributing
> modifications to keep track of from whom he is accepting code - either
> by using a version control system or in the file itself or a
> changelog. As far as the license of the code is concerned - it already
> in the same license as original because of the above point.

Not necessarily.  Contribution is only defined as an intentional
transmission of a modification to the Licensor.  Which is defined a
"the copyright owner or entity authorized by the copyright owner that
is granting the License."

Consider these examples.

Widget is a piece of software made by Sally.  Sally owns the copyright
and has licensed it under the ASL 2.0
Bob modifies Widget to add some feature to it.
Greg is a friend of Bob, who has no relationship or ownership interest
in anything Bob does.

1) Bob sends his modifications to Greg but doesn't specify the
licensing of his modifications.  The modifications are of an
indeterminate license since Greg is not the Licensor.  Bob is
obligated to have marked the files he sent to Greg specifying that he
did so and let's say they have the following statement "Modified by
Bob to add feature X"
2) Greg sends the modifications he received from Bob to Sally.  The
modifications are still of an indeterminate license since Bob did not
make the contribution.  Greg did not remove the modification notice
from the file.  Sally recognizes that Greg is not Bob and rejects the
contribution since it is not properly licensed.
3) Bob puts up a website and starts selling his version of Widget that
he calls Sprocket with the added feature.  He distributes Sprocket
under a typical commercial software license agreement that allows his
user to use one copy.  While all the unmodified pieces are licensed
under the ASL 2.0, the files that he modified are restricted by his
license agreement.  If Bob provides source, someone could take a file
out of his distribution that he had not modified and use it somewhere
else.  Thus the inclusion of the modification notice allows people to
identify the files still fully licensed under the ASL 2.0.  Note: As
Gervase wisely pointed out, anyone that does this should still do
their due diligence and should probably verify the files are really
not modified.
4) Bob sends his modifications to Sally and does not say anything
about licensing nor does he specify that this is not a contribution.
This constitutes a contribution and his modifications are licensed
under the ASL 2.0 since Sally is the Licensor.

As I was saying above what's not clear about the ASL 2.0 is if in 4)
above if Bob should include the modification notice in his
contribution and if Sally should leave the modification notice in
tact.  In practice I don't believe that the ASF is doing that
anywhere.  So that's part of my belief that the license does not
consider 4) to be redistribution.

But as you can see only in a very limited case are modifications
licensed under the ASL 2.0.

> Only issue remains is tracking the copyright owners - Does it make
> sense to enforce such a book-keeing clause in a license or rather
> leave it at the discretion of distributor of the Work to take the
> necessary steps to keep track of the copyright owners to protect
> himself.

As you can see above, this also helps protect the project from
accepting a contribution that would not automatically be licensed
under the ASL 2.0.