"A plenary indulgence, applicable ONLY to the souls in purgatory, may be obtained by those who, on All Souls Day, piously visit a church, public oratory, or - for those entitled to use it, a semi public oratory. It may be acquired either on the day designated as All Souls Day or, with the consent of the bishop, on the preceding or following Sunday or the feast of All Saints. On visiting the church or oratory it is required that one Our Father and the Creed be recited."