Date:        Tue, 17 Sep 2002 12:14:17 +0100
    From:        David Laight <david@l8s.co.uk>
    Message-ID:  <20020917121417.B1266@snowdrop.l8s.co.uk>

  | However a 'cleanroom' implementation has to be done from
  | documentation that is in the public domain (or some such
  | definition).  Using GPL source code isn't...

It wouldn't be a cleanroom implementation, but that doesn't mean it
would breach copyright.

eg: if I were to visit the Louvre, see a painting of a woman with an
enigmatic smile, and think "a painting like that might be a great thing
to give to the world", and race home and paint one - the result is not
necessarily a copy of the Mona Lisa - though it could be.   Whether it
is or not turns out to be a question of fact to decide in each case.

On the other hand, if I had never seen the painting (or a reproduction of
it), then no matter what my effort ended up looking like, it could not be
a copy.

That's why people like clean room implementations - not because it is
required for copyright purposes, but because it makes it absolutely clear
that there cannot be a copyright issue.

kre