Product announcement, edited, from Chloé Girard…
La Poule ou l’Oeuf is a free and Open Source online book editing program which lets you create multi-dimensional books.
The English name is The Chiken or the Egg.
You can insert notes, paragraphs, or entire sections of the book into different levels and let the readers activate them only when they want—with or without password authorization required.
You can activate or deactivate the two dimensions at the bottom of the left menu and have the notes visible or hidden. This can happen whether the notes are within the text or presented as footnotes.