The imposing script of the codex, described in contemporary calligraphy manuals as littera antiqua tonda, is a variant of the humanistic miniscule devised at the start of the fifteenth century by Florentine scholars following the research undertaken by Poggio Bracciolini.
The extremely elegant letters, which display both forcefulness and flexibility in their execution, are the work of six calligraphers, two of whom are, according to convention, known as Mano 1 and Mano 3 (‘hands’ 1 and 3).  It is quite clear that Mano 1 and Mano 3 were the more markedly talented calligraphers of the team, and it is thought they may have been, respectively,  Giovan Francesco Cresci, the author of Il Perfetto Scrittore (the perfect writer), and Marc’Antonio Rossi, the author of Il Giardino de Scrittori (the garden of writers).