The term CHURCH BOOK encompasses a variety of books used in religious services. The BIBLE, a collection of sacred texts, is the most well-known and widely used church book, with five letters. The MISSAL is a book containing the prayers and instructions for celebrating Mass, and has six letters. The BREVIARY is a book containing the daily prayers of the Divine Office, and has eight letters. The Psalter is a book containing the Book of Psalms, and has seven letters. The HYMNAL is a book containing hymns and other songs, and has six letters. Finally, the Ordo is a book containing the liturgical calendar, and has four letters.