Then I guess the answer is no. As far as I'm aware, comments have to be attached to a
bookmark or highlighted
note and are limited to 2048 characters.
No place to keep a separate "note pad" that is not associated with one of the above.
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This might be way out there, but you could create a document on your computer containing text that you could highlight and then add notes to. i.e.
Notes 1
Notes 2
Notes 3 ...
..or
Notes 1 2 3 4 5 6 7 8 9 10 ...
Reminder 1 2 3 4 5 6 7 8 9 10 ...
ToDo List 1 2 3 4 5 6 7 8 9 10 ...
Call this document "Notebook" and copy to reader as a book (and possibly create separate "Books" for Reminders and ToDo list).
Go to read your new "Notebook".
Comments could then be attached to each line or number in the book.
System keeps tracks of all notes and their dates.
Notes would have the title "Notes 1", "Notes 2", "Notes 3" etc., you couldn't change the note title, but the date it was written is displayed and might be enough of a clue to your note.
Not very pretty, but a possible work-around?