> Also, the argument is about reuse/interoperability. Recipes are something you use and the naming is functional and it is important that it is similar enough. I am not aware of harry potter chapters being used like that, but if authors start talking about "The sorting hat" chapter as a term of the art , then yes you should be able to use that term. Similarly to how you can introduce a weapon in your novel without paying royalties to Chekhov.

I agree very much. I just don't think books are very useful for expressing those ideas. Interoperability is rarely an important consideration when writing a book.