A scheme (Latin schema, plural schemata) is an arrangement of all or most of the psalms for distribution to the various canonical hours. In addition to the psalms proper, these schemata typically include psalm-like canticles from other books of the Bible. Historically, these schemata have distributed the entire 150 psalms with added canticles over a period of one week, although the 1971 Liturgy of the Hours omits a few psalms and some verses and distributes the remainder over a 4-week cycle. Some of the more important schemes are detailed below.
In addition to the psalms, the schema lists canticles, that is, biblical texts from outside of the book of Psalms that are chanted as if they were psalms.
In addition to the psalter, the schema uses an ordinary which includes the texts that are to be chanted every day. These include the Invitatory, normally psalm 94(95), and the canticles Benedictus Dominus, Magnificat, and Nunc dimittis.
Read more about this topic: Latin Psalters