Order of Mass is an outline of a Mass celebration, describing how and in what order liturgical texts and rituals are employed to constitute a Mass.
The expression Order of Mass is particularly tied to the Roman Rite where the sections under that title in the Roman Missal also contain a set of liturgical texts that recur in most or in all Eucharistic liturgies (the so-called invariable texts, or ordinary of the Mass), while the rubrics indicate the rituals, and the insertion points of the variable texts known as the proper of the Mass. Having been virtually unchanged for many centuries, the Roman Catholic Order of Mass changed decisively after the Second Vatican Council.
