I have one (so far) tune posted on ccMixter under the CC license. It contains a small segment of another artist’s work. As I wrote in the introduction to the tune, it is what I consider a draft. I have re-written the song, have removed the portion that is not my original work, added other tracks and altered the tune a bit. It is, effectively, a new song, although based on one I wrote which does have the CC license. Can I claim exclusive rights to the rewrite? I figure I can since it is entirely my creation and therefore my intellectual property, but what is ccMixter’s policy?

In general terms, ccMixter fits within regular copyright law (including publishing copyrights). It just uses specific licenses with the purpose to legally remix within regular copyright law.

If I understood you correctly, in ccMixter terms your first work would be considered a remix, the second one wouldn’t be.

And anything you post on ccM that is your intellectual property, remains your IP. By posting at ccM you just have licensed that work. Therefore you can reuse your own work in other contexts even after you have posted it at ccM.

Obligatory disclaimer: I’m not a lawyer, and this is not intended to be legal advice, and we don’t give legal advice around here - even those of us who are lawyers. :-)