The home of the Common Roman Pontiff Data Repository, curated by the Catholic Engineering Task Force of the Catholic Digital Commons Foundation.
The Common Roman Pontiff Data Repository (CRPDR) provides a canonicalized list of identifiers for the Roman Pontiffs, from Saint Peter to the reigning pope — 265 persons across 267 pontificates, seeded from the Holy See's own reference table of Roman Pontiffs.
Canonical papal identifiers are needed wherever Catholic data must reference a pope unambiguously:
- magisterial document attribution — encyclicals, apostolic constitutions,
and decrees are cited by their issuing pontiff (the
cdcf-uri-scheme already
builds
cdcf:magisterium/pope-leo-xiii/rerum-novarum-style URIs on papal slugs; CRPDR provides the maintained registry behind them); - liturgical calendar data, as served by the Liturgical Calendar API (papal feasts, canonizations, calendar reforms);
- Roman Martyrology cross-references (CRMEDR): many eulogies commemorate popes;
- episcopal succession data, church-history datasets, and any application that must say which pope it means.
rp:<name>-<roman-ordinal> e.g. rp:leo-xiv, rp:john-paul-ii
rp:peter (sole exception: Peter bears no ordinal)
Every identifier carries its ordinal — including sole holders of a name
(rp:francis-i, rp:lando-i) — so that IDs never shift when a future pope
reuses a name: the label "Pope Francis" may one day become "Pope Francis I",
but the identifier is immutable. Identity belongs to the person, not the
pontificate: Benedict IX, who reigned three separate times, is one
rp:benedict-ix with three pontificate records. The full proposal — grammar,
date handling, the Peter exception, antipopes, and the open questions — is in
docs/schema-proposal.md. All IDs are drafts
pending committee review.
data/pontiffs.json— the seed registry: 265 person records covering all 267 pontificates, each with its draft canonical ID, regnal name and ordinal, aliases, secular name, birthplace with the ISO 3166-1 alpha-2 code of its modern country, dated pontificates (source strings verbatim plus parsed dates where unambiguous), and itscdcf:person/cross-reference.registry/pontiffs.md— the same registry as a human-readable table, one row per pontificate in succession order.docs/schema-proposal.md— the proposed schema and the open questions for the committee.data/source/— the committed snapshot of the Holy See's table (provenance in its README); the generator parses this snapshot, never the live site.scripts/generate_seed.py— regenerates the seed (python3 scripts/generate_seed.py); tests:python3 -m unittest discover -s scripts.
The seed derives from the Holy See's reference table of Roman Pontiffs (vatican.va). The registry records the succession as the Holy See presents it; it takes no position on disputed historical questions.
The vatican.va table corresponds to the list of Roman Pontiffs that the Holy See publishes each year in the Annuario Pontificio, its official yearbook, compiled by the Central Office of Church Statistics of the Secretariat of State. The modern form of that list goes back to a critical revision by Angelo Mercati, prefect of the Vatican Secret Archive, adopted in the 1947 edition. The Annuario itself cautions that for some periods — the earliest centuries, and contested elections such as those of the mid-11th century — the dates and even the legitimacy of particular pontificates cannot be established with certainty; CRPDR inherits those uncertainties rather than resolving them.
Behind the Annuario stands a long tradition of historical sources. They are not used to generate the registry, but they are what our knowledge of the popes ultimately rests on, and they are the natural references for the committee when a record needs scrutiny:
- Early succession lists (2nd–4th centuries). Irenaeus of Lyons, Adversus haereses III.3.3 (c. 180), gives the Roman succession from Linus to Eleutherius, a list already circulating in Rome; Hegesippus (preserved in Eusebius) compiled a similar one. Eusebius of Caesarea's Ecclesiastical History and Chronicle (early 4th century) add reign lengths. The Liberian Catalogue, part of the Chronography of 354, runs to Pope Liberius with dates and consular years, and was a direct source for the Liber Pontificalis. Later lists appear in Optatus of Milevis and Augustine (Ep. 53).
- The Liber Pontificalis. A collection of papal biographies first compiled in Rome in the 6th century and continued, entry by entry, into the late 9th century, with medieval continuations reaching the 15th. Each life typically records origin (natione …), father's name, length of reign, ordinations, buildings and donations, and burial place. Its early entries are largely legendary or reconstructed; from about the 6th century it becomes a near-contemporary record kept in the papal administration. The standard critical edition is Louis Duchesne's (Le Liber Pontificalis, 1886–1892; supplementary volume by Cyrille Vogel, 1957); Theodor Mommsen edited the text to 715 for the Monumenta Germaniae Historica (1898). CRPDR already cites it where it documents a birthplace more precisely than the table (see the attested-birthplace notes in docs/schema-proposal.md).
- Papal registers. The Regesta Pontificum Romanorum calendar the surviving papal letters and acts — Philipp Jaffé's to 1198 (2nd ed. 1885–1888) and August Potthast's for 1198–1304 — and are a principal tool for dating medieval pontificates. The Vatican Apostolic Archive preserves the registers themselves: a continuous series from Innocent III (1198) onward, with earlier survivals such as the register of Gregory VII.
- Official acts (modern pontificates). Elections, deaths, and renunciations are recorded in the Acta Sanctae Sedis (1865–1908) and its successor, the Acta Apostolicae Sedis (1909–), the Holy See's official gazette.
The data and documentation in this repository are licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). See LICENSE for the full legal code.
The source code in scripts/ is licensed under the Apache License 2.0. See scripts/LICENSE.
The source snapshot data/source/holy-father-table.html is an excerpt of the Holy See's website (vatican.va), retained for provenance and reproducible generation. It is not covered by either license above; its reuse is governed by the Vatican Legal Notes.