This is a XVI c. parchment book of Gregorian chant. It is believed that it originated from Vilnius Bernardinee Monastery. The item is with defects – the title and the first 17 folios are missing. It is written in black square (Roman) notation using a four lines system. The text is splendidly rubricated in red, blue, and brown. The first part of the book of Gregorian chant is rich in jubiliation. The book was used for a very long time. In this book there are corrections and rubbing as well as chants written much later in different script and different notation. These corrections and the inscriptions of the new chants could have been made after the General Church Council in Trent and Reform of Church Music approved by it, e.g. using the same rhythmic values (brevis), the sequence Dies irae  was inscribed in the book much later then the book was rewritten.

There are also noticeable changes in the repertoire which has features of local music or music typical to the Order musical culture, as well as changes to the musical theory, e.g. an additional chant was introduced using two dieses and marked rhythmic caesuras (conditional bar lines) – the pre-clef signs that are not characteristic of Gregorian chant. Five line system was used when later inscribing certain chants written in square black notation (Kyrie eleison). One of parenthetic chants was inscribed using neumes of different notation. The book of Gregorian chant is interesting because of paleographic features. It provides information about that time prevalence of Gregorian chant traditions and local changes.