I have pushed an update to the Packaging for Apple Administrators book in the iBooks Store. Among a few typos and minor changes, I have added an Appendix section on legacy package formats.
If you already bought the book, you should be able to download the updated content for free. If you buy it now then you will get this update and any future ones!
If you have read and liked the book, please leave a review on the iBooks Store, I would be very grateful!