Paschal Triduum
Ash Wednesday, the ferias of Holy Week, the Paschal Triduum, and the days within the octaves of Easter and Pentecost (including the Ember Days of Pentecost) were classified as "ferias of the I class." The ferias of Advent from 17–23 December inclusive, the days within the octave of Christmas not impeded by the feasts of saints (29–31 December inclusive), as well as the Ember Days of Advent, Lent, and September were ranked as "ferias of the II class." The ferias of Advent, excluding 17–23 December, were ranked as "ferias of the III class," as were the ferias of Lent and Passiontide. In addition, the ferias of Lent and Passiontide were given precedence over all feasts of the III class, with III-class feasts reduced to commemorations in years in which they fell during Lent or Passiontide. The remaining ferias of the year were classified "ferias of the IV class."