I think the option of attaching a journal to specific sections of a book is really useful. Specially for reading math books where you need to do a lot of derivations.

I think it would be even more useful if we could attach a specific page in a journal to the pdf. So that when you click on the link in the pdf it will open the journal in the correct page.

That way we can have all out annotations in one journal instead of having a whole bunch of journals .