The
Baltimore Ceremonial thus classified the as a High Mass. The early 20th-century
Catholic Encyclopedia said, on the contrary, that a "is really a
low Mass, since the essence of high Mass is not the music but the deacon and subdeacon. Only in churches which have no ordained person except one priest, and in which high Mass is thus impossible, is it allowed to celebrate the Mass (on Sundays and feasts) with most of the adornment borrowed from high Mass, with singing and (generally) with incense." In 1960,
Pope John XXIII's
Code of Rubrics distinguished the both from a high Mass and from low Mass. Under the number 271, it defined the forms of Mass as follows: == Ceremonial ==