Most of my previous books have been released under a slightly different Creative Com- mons license, one that allowed for derivative works (that is, new creative works based on this one). Keen observers will have already noticed that this book is licensed “NoDerivs” -- that is, you can't make remixes without permission. A word of explanation for this shift is in order. When I first started publishing under Creative Commons licenses, I had to carefully explain this to my editor and publisher at To