>"Furthermore, we should think about having said checkbox checked by default rather than requiring users to understand what it is and why they might want to add this auto-generated code, especially if we can derive them automatically with confidence"
Imo, it does make more sensee to have checkbox checked by default, as I wasn't able to myself figure out what 'Automatically adding isbn would mean', when i am providing the value myself, so why to leave it to users to explore this feature. What are other views in this direction?