arguably the arrangement of chapters belongs to the book rather than the chapter That's a really excellent point, and array columns look like a really cool sol

arguably the arrangement of chapters belongs to the book rather than the chapter That's a really excellent point, and array columns look like a really cool solution! I suppose the only bummer is that it introduces a way to get things out of sync (I could delete a Chapter row, but forget to remove it from the array in Book), but in general this is a much better approach than the status-quo solution.