Development of Creative Commons licenses

[Ali Baba <mail.alibaba AT free.fr>]

> And that is the major reason why licences should not contain a clause
> allowinderivative material to be distributed under a licence other
> than the original one.

	So do you mean that a licence like BY-NC is pretty useless if not 
accompanied by SA? Or that every CC licence, even if not SA, forbids 
the distribution of derivative material under a different licence than 
the original one? If the latter, then what exactly does SA adds to a CC 
licence?

	Thanks.