ID Numbers: A History and Explanation | Cantus Manuscript Database

ID Numbers: A History and Explanation

Cantus IDs are 6-character codes, sometimes with letter-suffixes, that are assigned to unique texts within particular genres.

The first phase of Cantus chant ID numbers was based in the assignments given by René-Jean Hesbert in Corpus Antiphonalium Officii. These volumes, which index and provide the full texts of the chants found in twelve of the earliest Office antiphoners, include 4-digit numbers with letter-suffixes for some genres. For many years, chants occurring in Cantus inventories which were not included by Hesbert in CAO were assigned arbitrary 4-character numbers within each manuscript index. For example, "K302" identified a chant in Karlsruhe, Badische Landesbibliothek - Musikabteilung, Aug. LX, and "N255" identified a chant in Klosterneuburg, Augustiner-Chorherrenstift - Bibliothek, CCl 1010.

In a later development, two digits were added to the numbering system:

  • The prefix "00" now precedes all 4-digit CAO numbers making each "CAO"-sourced Cantus ID 6 digits (plus applicable letter-suffixes), thus preserving Hesbert’s assignments but allowing for future growth of the database;
  • New 6-digit numbers (plus applicable letter-suffixes) with numerical prefixes in accordance with Hesbert’s scheme ("10" = invitatories, "20" = antiphons, etc.) were created and assigned to all chants not included in CAO, in order that the chants could be cross-referenced among all sources in Cantus. At that point (in the early 2000s), all chants not included in CAO were reviewed and instances of the same chant in multiple sources were merged under a single, new 6-digit Cantus ID.

The third and current phase of numbering began after the implementation of Cantus Index, where users can enter new texts directly online for automatically-generated numerical assignments. The prefix designations "a", "g" and "h" were introduced which generally identify Office chants ("a"), Mass chants ("g"), and Old-Hispanic chants ("h"), although there is some crossover.


The six-number format and the “g#####”s, “a#####”s, and "h#####"s (plus suffixes) now identify each chant in Cantus Index and the Cantus Database.

Older designations of "CAO 1234" or "cao 1234" or "CANTUS ID 001234" now merge into a uniform format of "Cantus ID 001234".

Over three decades, Cantus has created tens of thousands of new identification numbers for individual chant texts. The Cantus numbers both incorporate and augment the system begun by Hesbert in CAO.

"ID Numbers: A History and Explanation" text updated by Debra Lacoste, 14 May 2024.