This ordinance applies henceforth, now, and forever, throughout all the provinces of the Christian world", exceptions were allowed from the start, and not all priests—even those within Latin Rites—were obliged to adopt the Missal of Pius V.[1]

In the bull Pope Pius V declared: "By this present Constitution, which will be valid henceforth, now, and forever, We order and enjoin that nothing must be added to Our recently published Missal, nothing omitted from it, nor anything whatsoever be changed within it."

And he concluded: "No one whosoever is permitted to alter this notice of Our permission, statute, ordinance, command, precept, grant, indult, declaration, will, decree, and prohibition.

In Missale Romanum, Paul VI states that the new liturgical norms are to be "firm and effective, now and in the future, notwithstanding, to the extent necessary, the apostolic constitutions and ordinances issued by Our predecessors, and other prescriptions, even those deserving particular mention and derogation.

[3] These provisions were later reversed by Pope Francis in his motu proprio Traditionis custodes, stating that "the liturgical books promulgated by Saint Paul VI and Saint John Paul II, in conformity with the decrees of Vatican Council II, are the unique expression of the lex orandi of the Roman Rite" and that all provisions contrasting with that were abrogated.