Wikidata:External identifiers
External identifiers are strings that represent identifiers used in external systems (databases, authority control files, online encyclopedias, etc.). They will display as external links in Wikidata items if a formatter URL (P1630) is defined.
Introduction edit
External identifiers link Wikidata items to databases, authority control files or encyclopedia articles about the item. Linking data to external sources can have many advantages for Wikidata:
- Data quality: cross-checking statements with other, academic sources
- Data completion: adding info like nationality, occupation, birth/death date/place from the external database
- Identifying missing notable items: by comparing Wikidata to other databases
- Popularise and motivate the use of Wikidata: the maintainer of the external database can be notified that Wikidata is integrating their IDs, they can enrich Wikidata and their own data (See: Q24075706)
- Supporting sister projects: for example providing references, further information links, etc., for Wikipedia
Wikidata External Identifier properties should have dedicated items to represent their values[1] and they should link to those using class of non-item property value (P10726).
External identifier items edit
An item should be created representing an external identifier as a class for the values that are values of the external identifier property.[1]
For example, the value of YouTube video ID (P1651) for Thank U, Next (Q60231842), "gl1aHhXnN1k", would be aninstance of (P31)YouTube video ID (Q110851517). Therefore YouTube video ID (Q110851517) would be the "external identifier item".
This is done so that the facts about the external identifier itself can be correctly described on the external identifier class such as who issued it with issued by (P2378) and how many of it exists with quantity (P1114).
The external identifier property is then linked to the external identifier item using class of non-item property value (P10726).
Properties edit
| Property | Description | Example |
|---|---|---|
| instance of (P31) | Type of identifier | unique identifier (Q6545185) |
| Wikidata property (P1687) | The property for this identifier | |
| issued by (P2378) | Who issued the identifier | |
| identifies (P10476) | The thing this identifier identifies | |
| quantity (P1114) | The number of identifiers of this type that exist.
It is known that this duplicates the data described by number of records (P4876) however no decision has been made yet as to which property to solely use. |
Properties that do not belong edit
| Property | Description |
|---|---|
| format as a regular expression (P1793) | The format of the value should be described solely on the property right now for consistency. |
Properties for identifiers edit
Required properties edit
| Property | Description | Example |
|---|---|---|
| instance of (P31) | defines the type of external identifier | |
| formatter URL (P1630) | web page URL; URI template from which "$1" can be automatically replaced with the effective property value on items. If the site goes offline, set it to deprecated rank. If the formatter url changes, add a new statement with preferred rank Multi-language sites: add the appropriate formatter for the different language URLs and use language of work or name (P407) as qualifier to specify the language and title (P1476) to add the name of the site in the particular language |
VIAF ID (P214) --> formatter URL (P1630): https://viaf.org/viaf/$1 |
| source website for the property (P1896) | URL of website acting as source of data for this Wikidata property Multi-language sites: add the appropriate URL for the different languages and use qualifiers language of work or name (P407) to specify the language |
GND ID (P227) --> source website for the property (P1896): https://portal.dnb.de |
| format as a regular expression (P1793) | regex describing an identifier or a Wikidata property. When using on property constraints, ensure syntax is a PCRE | IMDb ID (P345) --> format as a regular expression (P1793): ev\d{7}\/\d{4}(-\d)?|(ch|co|ev|nm|tt)\d{7} |
| class of non-item property value (P10726) | Class of the value of the external identifier | YouTube video ID (P1651)class of non-item property value (P10726)YouTube video ID (Q110851517) |
edit
| Property | Description | Example |
|---|---|---|
| language of work or name (P407) | language(s) of the external ID's site | Canadian Encyclopedia article ID (P5395) --> language of work or name (P407): English (Q1860), French (Q150) |
| applies to jurisdiction (P1001) | the identifier contains items that are located in/related to the value (country, state, city, region, ....) | Handbook of Texas ID (P6015) --> applies to jurisdiction (P1001) Texas (Q1439) |
| related property (P1659) | used to indicate another external ID that is similar in scope or topic | Handbook of Texas ID (P6015) --> related property (P1659): Encyclopedia Virginia ID (P5981) |
| Wikidata usage instructions (P2559) | text describing how to use a property or item | ORCID iD (P496) --> Wikidata usage instructions (P2559): Four groups of four digits, separated by dashes ("-") (English) |
| expected completeness (P2429) | describes whether a property is intended to represent a complete set of real-world items having that property | Values: |
| URL match pattern (P8966) | A regular expression that is supposed to match on a URL that contains the ID. It should also contain at least one group, that captures the id. | Encyclopædia Britannica Online ID (P1417) → ^https?:\/\/www\.britannica\.com\/((?:topic|place|event|science|technology|plant|animal|biography|sports|art)(?:\/[^\s\/]+)+)
|
Formatter properties edit
| Property | Description | Example |
|---|---|---|
| mobile formatter URL (P7250) | web page URL of mobile version; URI template from which "$1" can be automatically replaced with the effective property value on items | X username (P2002) --> mobile formatter URL (P7250): https://m.twitter.com/$1 |
| third-party formatter URL (P3303) | URI template from which "$1" can be automatically replaced with the effective property value on items; for sites other than the primary issuing body of the identifier concerned | MusicBrainz artist ID (P434): http://www.bbc.co.uk/music/artists/$1. DOI (P356) has many third-party sites, Legal Entity Identifier (P1278) has some |
| search formatter URL (P4354) | web page search URL; URI template from which "$1" can be automatically replaced with the string to be searched for | ORCID iD (P496) --> search formatter URL (P4354): https://orcid.org/orcid-search/quick-search/?searchQuery=$1 |
| formatter URI for RDF resource (P1921) | formatter URL for RDF (semantic) resource: URI template from which "$1" can be automatically replaced with the effective property value on items (it is the URI of the resources, not the URI of the RDF file describing it) | IdRef ID (P269) --> http://www.idref.fr/$1/id; Art & Architecture Thesaurus ID (P1014) --> http://vocab.getty.edu/aat/$1 (as opposed to http://vocab.getty.edu/page/aat/$1 |
Properties for documentation, usage edit
Properties for mapping, relations edit
| Property | Description | Example |
|---|---|---|
| equivalent property (P1628) | equivalent property in other ontologies (use property URI) | IMDb ID (P345) --> http://purl.org/ontology/mo/imdb |
| has characteristic (P1552) | use with component item if property is part of another identifier | Libraries Australia ID (P409) --> has characteristic (P1552): VIAF component (Q26921380), Qualifier: code (P3295): NLA |
| Mix'n'match catalog ID (P2264) | ID of the catalogue corresponding to the property in the mix'n'match tool | Kunstindeks Danmark Artist ID (P1138) --> Mix'n'match catalog ID (P2264): 91 |
Time lags and link consistency edit
It takes between 12 and 48 hours for the ID links to be operational. formatter URL (P1630) cannot be changed without a consensus of the community, even of the participants in the property proposal.