A tagging system makes sense if you think of the whole system as a collection of completely independent notes. You create a note, you add the tags, you search for tags to find what you want. But it doesn't make as much sense if you consider the notes to be related to each other. Suppose you're writing a book, and you've got one note per chapter, and the chapters themselves are further divided into a note per section. Now you want a note that collects up all the subnotes for the chapter, and a note that collects up all the chapters into a book, and the whole thing tied together with an integr