Another rung down: the memorial. First, a liturgical reminder for optional memorials falling during Advent, Christmas, Lent or Eastertime:
234. In the arrangement of the office there is no difference between obligatory and optional memorials, except in the case of optional memorials falling during privileged seasons.
Memorials During Ordinary Time
235. In the office of readings, at morning prayer, and at evening prayer:
a. the psalms and their antiphons are taken from the current week and day, unless there are proper antiphons or proper psalms, which is indicated as the case occurs;
b. the antiphon at the invitatory, the hymn, the short reading, the antiphons at the Canticles of Zechariah and of Mary, and the intercessions must be those of the saint if these are given in the proper; otherwise, they are taken either from the common or from the current week and day;
c. the concluding prayer from the office of the saint is to be said;
d. in the office of readings, the Scripture reading with its responsory is from the current cycle. The second reading is about the saint, with a proper responsory or one taken from the common; if there is no proper reading, the patristic reading for the day is used. The Te Deum is not said.
236. At daytime prayer and night prayer, all is from the weekday and nothing is from the office of the saint.
Memorials During Privileged Seasons
237. On Sundays, solemnities, and feasts, on Ash Wednesday, during Holy Week, and during the octave of Easter, memorials that happen to fall on these days are disregarded.
238. On the weekdays from 17 to 24 December, during the octave of Christmas, and on the weekdays of Lent, no obligatory memorials are celebrated, even in particular calendars. When any happen to fall during Lent in a given year, they are treated as optional memorials.
239. During privileged seasons, if it is desired to celebrate the office of a saint on a day assigned to his or her memorial:
a. in the office of readings, after the patristic reading (with its responsory) from the Proper of Seasons, a proper reading about the saint (with its responsory) may follow, with the concluding prayer of the saint;
b. at morning prayer and evening prayer, the ending of the concluding prayer may be omitted and the saint’s antiphon (from the proper or common) and prayer may be added.
Memorials of the Blessed Virgin Mary on Saturday
240. On Saturdays in Ordinary Time, when optional memorials are permitted, an optional memorial of the Blessed Virgin Mary may be celebrated in the same way as other memorials, with its own proper reading.
Rather more detailed if you’re looking at the calendar as a whole, but important stuff if your parish or religious community has a special saint for whom a LH observance is merited. Comments?