I class
Violet
IV Sunday of Advent vacat – no commemoration
The traditional fast and abstinence are not observed because the Vigil falls on Sunday this year
The Season of the Nativity begins with I Vespers
Proper Mass. Because the Vigil is on Sunday this year, the Alleluia and its verse are included after the Gradual, the Credo is used, and the preface is of the Holy Trinity (or of Advent, but not the common preface used on ferias). The Gloria is not used, however, because it is still a Mass of Advent with violet vestments.
Matins: Invitatorium Hodie scietis and Hymn in Tempore Adventus; antiphons and psalms of the feria; proper verse; lessons from the homilia in Evangelium diei; no Te Deum
Lauds: Proper Antiphons and Sunday psalms (1st schema); remainder proper
Prime: Antiphon from Lauds, with Sunday psalms (Psalm 53 instead of 117); remainder proper
Hours: Sunday psalms with antiphons from Lauds; remainder proper
I Vespers: Of the Nativity of the Lord; proper antiphons with Sunday psalms, except Ps. 116 as fifth psalm; remainder proper; no commemoration of Sunday
Compline: Of Sunday; Nativity versicle (Post partum) after Marian antiphon until February 1