Hannah Schroeter <hannah@schlund.de> writes:

quoted text
> Right. You may add nearly any copyright *on your own significant
> additions/changes*.

Such as a patch? Hardly IMHO, a patch is not a work but an output
of an automated tool. The copyright is not about fragments of works.

You may add a copyright _notice_, not a copyright (a right).
The author of a derived work automatically has copyright to the
whole derived work, not only to the "fragments" he has created.
MS Windows is "Copyright Microsoft", not "Microsoft and others".

You can add any licence (not copyright, as it's automatic) to your
(derived or not) work. If it's a derived work, you must comply with
the original licence(s).

Of course, the original work is copyrighted by its original author
and licenced under its original conditions, and nobody is able to
change that.

Now, you don't need a licence from the original author to use
the derived work. The author of the derived work only needs
a licence from the original author to create a derived work.
Do you think Microsoft users have licences from authors of
the works MS Windows etc. are based on? :-)

You do need a licence from the original author to use the original
work, e.g. unmodified original work distributed by third party.
I.e., you don't need a licence to use MS Windows from the retail
shop, you need it from MS.

Is it that hard to understand?

quoted text
> However, BSD/ISC explicitly requires to retain the
> BSD/ISC terms, too (applicable to the original part of the combined
> work).

Where exactly?
Have you seen MS EULA maybe?
Such requirement would be impossible to fullfit.

quoted text
> No. The derivative work altogether has a *mixed* license. BSD/ISC for
> the parts that are original, the other (restrictive, GPL, whatever)
> license for the modifications/additions.

Look at MS EULA, does MS Windows in your opinion have such a mixed
licence too? :-)
-- 
Krzysztof Halasa