MPL (and APL) license issues

[Fabio Alemagna]

Hello everyone,

I'm one of the AROS (http://aros.sf.net/) developers, and I'm here to ask
something about the AROS Public License (APL) and indirectly about the
MPL, which the APL derives from (basically, everything is kept intact,
apart from the Mozilla refereces changed into AROS references).

>From my understanding of the license, people are allowed to modify the
source code as long as they provide the sources of their modifications,
where "modifications" means:

    "any addition to or deletion from the substance or structure of either
     the Original Code or any previous Modifications. When Covered Code is
     released as a series of files, a Modification is:

      A. Any addition to or deletion from the contents of a file
         containing Original Code or previous Modifications.

      B. Any new file that contains any part of the Original Code or
         previous Modifications."

Now, look at this situation.

Say I have a set of files, named A. Now, Mr. Brown takes these files,
modifies them, and produces a new set of files which is the union of A'
and B, where A' is the set of files which are the modifications of the
files in the set A, and B is a set of new files.

As I understand it, Mr. Brown only has to release the sources of A',
right? If I'm right, please follow me: what happens if A' _doesn't_ work
without B? In other words, if Mr. Brown modified A in such a way that now
A' depends on B and B depends on A'? Is Mr. Brown still required to only
open the sources of A'? If yes, isn't this a big hole in the license? If
not, in which way exactly the license would require Mr. Brown to also
opensource B?

In yet other words, do the modified sources need to be completely
functional, or can they also not work at all without the
"proprietary" part?

Regards,
Fabio Alemagna

--
license-discuss archive is at http://crynwr.com/cgi-bin/ezmlm-cgi?3