As much by the density and the rhythm of its publications as by its license of open diffusion, the blog S.I.Lex forms a “book in continuous progress”, quoting Hervé Le Crosnier. However, the blog of Lionel Maurel is not so easy to seize by a publisher. The collection La Numérique from the Presses de l’École nationale supérieure des sciences de l’information et des bibliothèques (Enssib) is experimenting with making a free digital book from the S.I.Lex blog by investing on forms of editorialization that question the place of the author and readers, the value of the free, and the role of the digital environment.