Development of Creative Commons licenses

[wiki_tomos <wiki_tomos AT inter7.jp>]

This is not a new question, but since it has been embedded 
in various contexts, I thought I would just make a
separate post dedicated to it. 

The issue is about the effect of external communication on 
the interpretation and effects of the license. 

For example, what happens when I say "this work is 
licensed under CC-BY-SA, but please do not use it for a 
musical," or "this work is licensed under CC-BY-SA, but 
you can skip the attribution to me if you want," etc?

There are certain parts of CC-BY-SA (and other CC licenses) 
that seemingly make those external communication ineffective. 

Foreword "ANY USE OF THE WORK OTHER THAN AS AUTHORIZED UNDER THIS 
LICENSE OR COPYRIGHT LAW IS PROHIBITED." 

8d."No term or provision of this License shall be deemed 
waived and no breach consented to unless such waiver or 
consent shall be in writing and signed by the party to be 
charged with such waiver or consent."

8e. "This License constitutes the entire agreement between 
the parties with respect to the Work licensed here. There 
are no understandings, agreements or representations with 
respect to the Work not specified here. Licensor shall not 
be bound by any additional provisions that may appear in 
any communication from You. This License may not be modified 
without the mutual written agreement of the Licensor and You."

I can think of a list of factors that I wonder might matter 
in determining external communication's effect. Timing of 
the communication, if it is intended to add license 
restrictions or reduce them, etc. But I don't know if they 
are relevant. So I will end here instead of going into more 
discussions. 

Best, 


Tomos