I.

(Choralbuch) is a collective term for collections of Gregorian chant. Since the 10th century, these have included the gradual, cantatorium, troper, sequentiarium, kyriale, antiphonary (Antiphon), hymnary, processional, tonary, and directory/breviary/ordinary. Since 1905, the Editio Vaticana has published new editions for practical use. The formerly common Liber usualis (Antiphonary) has been made obsolete by liturgical reform. The collections in use today are the Graduale Romanum (1974) or Graduale triplex (1979)…