---
id: "ocn"
kind: "datatype"
status: "stable"
is_pii: false
categories: ["objectids"]
langs: ["common"]
quality: 70
url: "http://registry.apicrafter.io/datatype/ocn"
---

# OCLC Control Number (`ocn`)

OCLC assigns a unique control number (referred to as an "OCN" for "OCLC Control Number") to each new bibliographic record in the WorldCat. Numbers are assigned serially, and as of mid-2013 over a billion OCNs had been created. In September 2013, the OCLC declared these numbers to be in the public domain, removing a perceived barrier to widespread use of OCNs outside OCLC itself.[42] The control numbers link WorldCat's records to local library system records by providing a common reference key for a record across libraries

- Personal data (PII): no
- Categories: Objects identifiers (objectids)
- Countries: global
- Languages: Common to most languages (common)
- Classification: identifier

## Detection

Regular expression (Python `re`):

```
\d{1,14}
```

## Examples

- `787911721` — Directory of Open Access Books
- `57722711` — Iso suomen kielioppi

## Mappings

- bioregistry: `oclc`
- wikidata: `P243`

## Sources

- wikipedia: <https://en.wikipedia.org/wiki/OCLC>
- wikidata: <https://www.wikidata.org/wiki/Property:P243>

## Quality

Score 70/100. Missing: anchored regexp, negative example, translation, detector coverage.

JSON: <http://registry.apicrafter.io/api/v1/datatypes/ocn.json> · Edit: <https://github.com/apicrafter/metacrafter-registry/edit/main/data/datatypes/any/objectids/ocn.yaml>