In the Roman Catholic Mass, it is the first item, the chant sung as the priest enters and approaches the altar. In the Anglican service, it is a short anthem, hymn, or psalm sung as the minister prepares to administer communion. the introductory chant of the mass, sung by the choir; it is proper (its text changes from day to day) and antiphonal. Its form is antiphon--psalm--antiphon--doxology--antiphon, though the antiphon between the psalm and doxology may be omitted. It is the only chant of the mass to use the lesser doxology. the initial chant of the mass proper