Liturgical book
A liturgical book, or service book, is a book published by the authority of a church body that contains the text and directions for the liturgy of its official religious services. Christianity. Roman Rite. In the Roman Rite of the Catholic Church, the primary liturgical books are the Roman Missal, which contains the texts of the Mass, and the Roman Breviary, which contains the text of the Liturgy of the Hours. With the 1969 reform of the Roman Missal by Pope Paul VI, now called the "Ordinary Use of the Roman Rite", the Scriptural readings were expanded considerably , requiring a separate book, known as the Lectionary. The Roman Ritual contains the texts of the sacraments other than the Mass, such as baptism, the sacrament of penance, the anointing of the sick, and the sacrament of marriage. The texts for the sacraments and ceremonies only performed by bishops, such as confirmation and Holy Orders, are contained within the Roman Pontifical. The "Caeremoniale Episcoporum" ("The Ceremonial of Bishops") describes in greater detail than the ordinary liturgical books the ceremonies involved when a bishop presides over the celebration of Mass, the celebration of the Liturgy of the Hours or of the  Word of God, particular Masses such as Candlemas, Palm Sunday or the Easter Vigil, the other sacraments, sacramentals, pastoral visitations etc. The Roman Martyrology gives an account of all the saints (not only martyrs) commemorated in the Church each day. Other Roman-Rite liturgical books include the Roman Gradual and the Gospel Book or Evangeliary. The Catholic Church is composed of 24 autonomous particular churches, the largest of which is the Latin or Western Church. The other 23 churches are collectively called the Eastern Catholic Churches, and use a variety of liturgical rites such as the Alexandrian Rite, Antiochene Rite , Armenian Rite, Byzantine Rite, and the East Syriac Rite among others. While the Roman Rite of the Western Church is by far the most common liturgical rite found within the Latin Church, a number of local Western (but not Roman) rites and uses also exist. Byzantine Rite. The Rite of Constantinople, observed by the Eastern Orthodox Church and those Eastern Catholic Churches which follow the Byzantine Rite, represents one of the most highly developed liturgical traditions in Christendom. While the Roman Catholic Liturgy of the Hours may be published in a single-volume breviary, such a feat is hardly possible  for the Byzantine Rite, which requires quite a large library of books to chant the daily services. The regular services chanted in the Constantinopolitan liturgical tradition are the Canonical Hours and the Divine Liturgy. There are, in addition, occasional services (baptism, confession, etc.) and intercessory or devotional services (molieben, panikhida), which are not chanted on a daily basis, but according to need. The fixed portions of the services are called "acolouthia" (, ; ), into which the "sequences" (changeable portions) are inserted. The sequences can also be referred to as "propers" The sequences are governed by the convergence of several liturgical cycles, including  the Paschal Cycle (movable cycle, dependent upon the variable date of Easter) and the Menaion (fixed cycle, dependent upon the calendar date). Acolouthia. The fixed portions of the services are found in the following liturgical books: Sequences. Into this fixed framework, numerous movable parts of the service are inserted. These are taken from a variety of liturgical books: