The Liber Usualis is a book of commonly-used Gregorian chants compiled by the monks of the Abbey of Solesmes in France. This 1,900-page book contains most versions of the ordinary chants for the Mass (Kyrie, Gloria, Credo, Sanctus, and Agnus Dei), as well as the common chants for the Divine Office (daily prayers of the Church) and for every commonly celebrated feast of the Church Year (including more than two hundred pages for Holy Week alone). The "usual book" or "common book" also contains chants for specific rituals, such as baptisms, weddings, funerals, ordinations, and benediction. This modal, monophonic Latin music has been sung in the Catholic Church since at least the sixth century and through the present day. An extensive introduction explains how to read and interpret the medieval musical notation (square notation of neums or neumes). A complete index makes it easy to find specific pieces. The Liber was first edited in 1896 by Solesmes abbot Dom André Mocquereau (1849 1930).