Kathy or Bert,
First of all, I'd like to say that this book is great! Topics are presented in a way that actually makes it fun to read.
Just had one suggestion... Would it be possible to create another errata page (in addition to the existing one) which appends the newest changes chapter by chapter to the end of the last version of the errata? So for example, the next errata page would contain March version plus new changes appended to the end. This would make it a lot easier to review these changes and update the book as each new version of the errata comes out.
I hope other people will find this helpful as well.