URN - Uniform Resource Name
What is a URN identifier?
A URN identifier is a unique and persistent identifier of an electronic document. Once given to a document the identifier remains unaltered as long as the name and the contents of the document remain intact. Same identifier is never assigned to two separate documents. The URN identifier can be exploited as a persistent web address through registering.
The National Library of Finland's URN register works as a decentralized service for Finnish universities and other institutions. Currently private persons cannot register URN-identifiers.
URN registration and persistent URL
Assigned URN identifiers and corresponding URLs must be registered at the National Library. A persistent web address comprises of the URN identifier prefixed with the address of the resolving service. For example:
- ISBN number of a document is 952-10-0093-7;
- URN identifier of the document is therefore URN:ISBN:952-10-0093-7;
- The persistent web address of the document is thus http://urn.fi/URN:ISBN:952-10-0093-7.
The resolving server redirects to the current location of the document. When the document is moved, the change will be registered and thus the persistent address remains functional.
The publisher may register URN identifiers manually, but usually the data are updated automatically from the publisher’s system, e.g. the institutional repository.
Generating a URN identifier
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If a document is eligible for an ISBN or an ISSN number, it will be assigned one, and the URN identifier is based on it.
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If a document may not be given an ISBN or an ISSN number, it will be assigned a NBN number.
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Identical copies of a document get the same URN identifier. Therefore, a URN based web address may resolve successfully to several URLs.
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If a document is edited, a new URN identifier is only assigned if the contents change significantly.
- URN:NBN numbers are assigned to web documents only
NBN numbers may be obtained from the URN generator maintained by the National Library. A publisher may apply for a NBN sub-namespace and generate numbers independently.
Displaying the URN identifier in a document
URN:ISBN and URN:ISSN identifiers must be both displayed in writing in the body of the document (if applicable) and recorded in its metadata.
The manner of writing a URN identifier is as follows:
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URN:ISBN:951-611-441-5
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URN:ISSN:1234-5678
The identifier should be recorded in the embedded metadata, too. For example, in an HTML document, it should be entered in the HEAD section:
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META NAME="Identifier" SCHEME="URN:ISBN" CONTENT="951-611-4415"
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META NAME="Identifier" SCHEME="URN:ISSN" CONTENT="1234-5678"
URN:NBN identifier should be displayed in the same way, if possible. If a URN is assigned to a document after it is finished, it is not strictly obligatory to add it to the document body.
URN:NBN is expressed in following ways:
- URN:NBN:fi-fe20042357
- META NAME="Identifier" SCHEME="URN" CONTENT="URN:NBN:fi-fe19981001"
In creating metadata, one can use the Dublin Core metadata generator.
URN standards
URN identifier is specified in so called Internet standards of IETF (Internet Engineering Task Force)
Using ISBN numbers as part of a URN identifier is specified in RFC 3187; ISSN numbers, in RFC 3044; and NBN numbers in RFC 3188. URN syntax is specified in RFC 2141.
- RFC 3187
- RFC 3044
- RFC 3188
- RFC 2141
Contact
- e-mail: e-vapaa@helsinki.fi
- Tel. ISBN Agency, +358-9-191 44327
