s. XVI. BOOK: (CHOIR BOOK). IN NATIVITATE DOMINI DA MANTUTINUM. INVITATORIUM. Part of a choir book on parchment in large sheet (54 cm). Folio XXV and XXXII (2 h.) manuscripts in recto and verso. In two inks, pentagram in red and square notation in black. Large capitals in red and blue. First and only heading preserved 'in nativitate domini ad matutinum, begins: 'Christus natus est nobis'. The foliation indicates that these are the initial and final leaves of a sheet containing an antiphonary, which in the part that has been preserved corresponds to the liturgical office of the Christmas feast (matins).