"Share similarly" wording
The wording in CC-BY-SA is:
- "If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one".
I was under the impression (on account of something I read by David Wiley a long time ago) that CC ShareAlike meant one would have to release derived works under exactly the same license. The above wording does not say that. So, I am assuming that "similar license" means 'similar in intent'. In this case, the new license would have to retain the 4 freedoms and require them in derived works.