Every hymn begins with a verset with a continuous "cantus firmus": the hymn melody is stated in long note values in one of the voices, usually the bass, while the other voices provide contrapuntal accompaniment. Other versets are only occasionally cast in this form. More frequently the 16th century motet practice is used: the hymn melody either migrates from one voice to another, with or without imitative inserts between verses, or is treated imitatively throughout the piece. In three versets ("Veni Creator" 3, "Ave maris stella" 3, and "Conditor" 2) the melody in one voice is accompanied by two voices that form a canon, in two ("Ave maris stella" 4 and "Annue Christe" 3) one of the voices provides a pedal point. In most versets, counterpoints to the hymn melody engage in imitation or fore-imitation, and more often than not they are derived from the hymn melody. All of the pieces are in four voices, except the canonic versets, which use only three.