Liturgical Ministries
In liturgical celebrations each one, minister or layperson, who has an office to perform, should do all of, but only, those parts which pertain to that office by the nature of the rite and the principles of liturgy.
Servers, readers, commentators, and members of the choir also exercise a genuine liturgical function. They ought to discharge their office, therefore, with the sincere devotion and decorum demanded by so exalted a ministry and rightly expected of them by God’s people.
Constitution on the Sacred Liturgy, nos. 28-29