Understanding what a copy is
mmm I see the problem -- a tough one to explain clearly (hence all the legal debates on what constitutes a derivative work.
A digital copy is a "verbatim" copy and prohibited under copyright law (because its a copy :-)
So legally we must keep the sentence ""Under general copyright law, format shifting from one medium to another is considered a copy."
So I suggest deleting "and therefore a derivative work." from the original sentence.
Should we add an example of format shifting after this sentence:
"For instance, if you have a digital image in jpeg format, converting the same image to another format, for example, the gif file format, that would be a copy and not permitted under general copyright law.
I think I'm starting to understand what this paragraph is about. I don't think I got it before. I made a few changes, incorporating your suggestions as well as other wording, to improve the explanation. See what you think.
Actually, now that I "think" I understand it, this seems to be a big point--the idea that CC allows copies, to some extent for all of the licenses even when the license includes ND.