sentences:  These are services of a similar structure to, but briefer than, the hours.their usage varies with local custom, but generally they are used only during the Nativity Fast, Apostles Fast, and Dormition Fast on days when the lenten alleluia replaces "God is the Lord" at matins, which may be done at the discretion of the ecclesiarch when the Divine Liturgy is not celebrated.In addition to these public prayers, there are also private prayers prescribed for both monastics and laypersons; in some monasteries, however, these are read in church.