Universal Norms on the Liturgical Year and the General Roman Calendar

Universal Norms on the Liturgical Year and the General Roman Calendar is the Catholic Church's own official norms, issued by Pope Paul VI's motu proprio Mysterii Paschalis in 1969, restructuring how the Roman Rite ranks and dates its liturgical year. It is authoritative for the Church's own official dating and ranking of holy days such as Lent, Holy Week and the fixed and movable feasts, checkable directly against the document's own text, not for how other Christian traditions calculate the same or related holidays, since this is a normative document specific to the Roman Rite. Use it to establish the Roman Catholic Church's own current liturgical calendar rules; a claim about a different Christian tradition's calendar needs a source from that tradition instead.