Of the 1293 signatures in the fond, only 1287 items are still held, and of these 91 have been digitized. This collection is one of the only two in the Vatican that exclusively contains music, the other being Vat.mus. It was the library of the Cappella Giulia, officially called Reverend Musical Chapel Julia of the Sacrosanct Papal Basilica of Saint Peter in the Vatican. This is the choir that sings all the Liturgy at St. Peters when the pope is not in attendance. The collection spans the 16th through the 20th C, and the majority of the books are printed. The collection was transferred to the Vatican libraries in 1941, despite the strenuous objection of the then Master of the Chapel, Ernesto Boezi.
At the moment, most of the digitized copies are simply scans of microfilm, though a few are in color including the beautiful Medici Chansonnier, Capp.Giulia.XIII.27. To the right is the first page of music, f.7v
Sources
Biblioteca apostolica vaticana. (2011). Guida ai fondi manoscritti, numismatici, a stampa della Biblioteca vaticana. Biblioteca apostolica vaticana. pp. 384-388