Pseudepigrapha — who authored the letter/book
Literal Authorship — the author wrote with their own hand, from their own mind the letter/book
Dictation — the amanuensis/secretary had to write word for word what the author said
Delegated Authorship — the amanuensis/secretary freedom in crafting the letter
Posthumous Authorship — author dies before the letter is completed and the amanuensis/students would finish the letter
Apprentice Authorship — a student or school continues to write letters in the name of the author after they dies
Honorable Pseudepigrapha — admirers write in the authors name
Forgery — writing in another name without any authority