On Dec 3, 2007 12:59 PM, drew Roberts <zotz(a)100jamz.com> wrote:
OK, CC BY is not copyleft at all.
CC BY-SA as it stands now is a weak copyleft (as we are speaking of weak here)
This is, however, a disputed point: CC-By-SA even includes examples of
new works which would be required to be cc-by-sa licensed, such as the
movie which results from adding images or video to a covered sound
recording.
From by-sa-2.5: "'Derivative Work' means
a work based upon the Work
or upon the Work and other pre-existing works, (...) or
any other form
in which the Work may be recast, transformed, or adapted, except that
a work that constitutes a Collective Work will not be considered a
Derivative Work for the purpose of this License. For the avoidance of
doubt, where the Work is a musical composition or sound recording, the
synchronization of the Work in timed-relation with a moving image
("synching") will be considered a Derivative Work for the purpose of
this License."
When Creative Commons adopted the position that cc-by-sa covered
images do not enjoy the same protection as sound in situations where
it is synchronized with sound or text it was shocking and upsetting to
a number of people.
So while it's the whole weak/strong copyleft issue needs to be fleshed
out, I don't think it's fair to just state that cc-by-sa is currently
a weak copyleft, even if that is the intention of the licenses'
stewards with respect to visual works.