A book is typically divided into sections, chapters, paragraphs. I'm looking for a noun that can be used to describe all of these - book, sections, chapters, figures, clusters of paragraphs and individual paragraphs - in a way that can be used recursively.
I'm thinking perhaps something around the word "idea", but not sure what exactly and would appreciate other suggestions.
Updated: I'd like a word that applies equally well to books as well.
Updated again: If possible, I'd like also to be able to apply it to diagrams, tables and other such figures.
It does not need to apply to the contents or index in the book.