ANSI / NISO Z39.88-2004 (R2010)
OpenURL
An independent reference for the OpenURL Framework — the standard for encoding bibliographic citations and context-sensitive service requests inside URLs.
OpenURL is a NISO standard, ANSI/NISO Z39.88-2004 (approved by ANSI in 2005, reaffirmed in 2010), that defines how a citation or resource description can be carried inside the query string of a URL together with the context of the request. Its most common use is in scholarly publishing: a database links to an article, the user's institutional link resolver intercepts the request, and the user is delivered to a copy their library can actually grant access to. The same framework covers books and chapters, dissertations, patents and conference papers.
This site is an independent, openly maintained reference. It is not affiliated with NISO or with OCLC, which served as maintenance agency and ran the OpenURL Registry at openurl.info until the Registry was frozen in 2022. The goal here is to keep the standard documented, examples available, and the framework usable for the developers, librarians, and information-systems builders who continue to depend on it.
Contents
The Standard
Architecture, versions, and the parts that make up an OpenURL.
- 01What is OpenURL?A plain-language introduction.
- 02The Z39.88-2004 StandardScope, structure, and conformance.
- 03OpenURL 0.1 vs 1.0What changed, what still works.
- 04Anatomy of an OpenURLBase URL, query string, key/value pairs.
- 05The ContextObjectThe payload carried by every OpenURL.
- 06TransportsBy-Value, By-Reference, and Inline.
- 07The KEV FormatKey/Encoded-Value serialization.
- 08The XML FormatContextObject as XML.
- 09Community ProfilesSAP1, SAP2, and how profiles work.
- 10The OpenURL RegistryFormat identifiers and namespaces.
- 11IdentifiersDOI, ISBN, ISSN, PMID, info: URIs.
Entities
The six entities of the ContextObject.
- 12Entities OverviewReferent, Referrer, and the rest.
- 13Referent
rftThe resource being described. - 14ReferringEntity
rfeThe resource referencing the Referent. - 15Requester
reqThe party requesting service. - 16ServiceType
svcThe type of service requested. - 17Resolver
resThe target of the request. - 18Referrer
rfrThe entity that generated the ContextObject.
Metadata Formats
The bibliographic formats in KEV and XML, plus Dublin Core.
- 19Journal — KEVArticles, issues, journals.
- 20Book — KEVBooks, chapters, proceedings.
- 21Dissertation — KEVTheses and dissertations.
- 22Patent — KEVPatent applications and grants.
- 23Journal — XMLXML schema and elements.
- 24Book — XMLXML schema and elements.
- 25Dissertation — XMLXML schema and elements.
- 26Patent — XMLXML schema and elements.
- 27Dublin Core — KEVThe fifteen DC elements as
rft.*keys.
Worked Examples
Valid OpenURLs you can copy and adapt.
- 28Journal Article by DOIUsing
rft_id=info:doi/… - 29Journal Article by MetadataWhen no identifier is available.
- 30Book by ISBNThe canonical book example.
- 31Chapter in an Edited BookUsing
genre=bookitem. - 32Conference PaperProceedings and papers.
- 33Dissertation or ThesisInstitution, advisor, degree.
- 34PatentPatent number, country, kind.
- 35Preprint (arXiv)Identifying a preprint server item.
Tools
Client-side utilities. No data leaves your browser.
Ecosystem
How OpenURL fits with the rest of the citation stack.
- 39Link ResolversWhat they are and how they use OpenURL.
- 40OpenURL & DOICarrying DOIs inside OpenURLs.
- 41OpenURL & CrossrefThe Crossref OpenURL endpoint.
- 42OpenURL & COinSEmbedding ContextObjects in HTML.
- 43OpenURL & KBARTKnowledge bases and link quality.
- 44ImplementationsOpen-source parsers and builders.
History & Context
How the standard came to be, and where it stands today.
Guides
Practical answers for librarians, developers and researchers.