What do the three calendar models cover?
The pre-1955 choice uses 1954 as its last full baseline before the simplified rubrics took effect on January 1, 1956. It does not claim that every year from 1911 through 1954 had an identical calendar. The 1962 Roman Missal choice applies the Code of Rubrics promulgated in 1960 and required from January 1, 1961. The current choice uses the General Roman Calendar, updated through February 2026.
Each choice is a universal Roman calendar projection for the civil dates entered. It is not an archival copy of the annual Ordo printed for a particular place.
Does the calendar include diocesan or national feasts?
No. The engine does not add diocesan, national, monastic, religious-order, or community propers. The modern Sunday-transfer controls affect Epiphany, Ascension, and Corpus Christi only. They do not turn the universal model into a national calendar.
What does a row in the results mean?
Each civil date has one principal result. Optional celebrations are listed as choices. Other losing candidates remain unclassified unless a source and rule establish their disposition. An unclassified candidate should not be read as a commemoration or transfer.
How are today and date ranges handled?
The opening comparison uses the civil date and time zone reported by your device. A selected date range is inclusive. Downloaded files contain that full selected range, even when the onscreen table has a text filter applied.
What has the calendar been checked against?
The automated evidence set contains six complete-year fixtures preserving 2,192 cited civil dates. They include a 1952 diocesan Ordo, a universal 2007 Ordo using the 1962 books, the 1970 general-calendar schema, and official United States calendars for 2024 through 2026. Local entries stay visible in the research but are excluded from universal-calendar defect claims.
What are the known limits?
Full Office occurrence and concurrence, every historical octave and vigil distinction, and every transfer or commemoration branch are not yet represented. Complete primary-source coverage is also thin for 1955, 1956, 1960, 1962, and the early postconciliar years.
For liturgical use, compare the result with an approved Ordo for the jurisdiction, community, and year concerned.