Each quaternion gathering would be numbered in the bottom right corner. A new letter is used for each quire, eg A, B, C, D... And within each quire only the rectos were numbered, A1, A2, A3 and A4.
This numbering is called the Quire-signature. It helps the binder to ensure the pages are in the correct order and then, using the lettering scheme, to ensure the cahiers or quires are in the correct order in the book.
Please take a look at the image again, notice the white question-mark, then try the exercise below
Please copy your answers to your own electronic notes