NISOOpenURL is a NISO standard (ANSI/NISO Z39.88-2004) that defines a framework for packaging bibliographic metadata into URLs and transporting them to context-sensitive link resolvers. It is a foundational technology in academic library infrastructure, enabling the seamless routing of users from citation databases to the full text of articles, books, and other resources available through their institution's subscriptions.
Background
In the late 1990s, the proliferation of electronic journals and databases created a new problem for libraries: how to connect users from a citation in one system to the full text in another, taking into account each institution's unique collection of subscriptions. Herbert Van de Sompel, then at Ghent University, developed the original OpenURL concept around 1999-2000 as a way to encode bibliographic metadata in a standardized URL format that a local resolver could interpret. The informal OpenURL 0.1 gained rapid adoption, and NISO undertook formal standardization, publishing ANSI/NISO Z39.88-2004, "The OpenURL Framework for Context-Sensitive Services," in 2004.
Purpose & Scope
An OpenURL packages metadata about a referenced resource (the "referent") along with contextual information about where the user is coming from (the "referring entity"), who the user is (the "requester"), and what service is being sought (the "service type"). This metadata package is sent as a URL query string to a link resolver, which uses the information to look up the resource in a knowledge base of institutional holdings and present the user with appropriate access options.
The standard defines several key components:
| Component | Description |
|---|---|
| Referent | The resource being sought (article, book, patent, etc.) |
| ReferringEntity | The source from which the OpenURL was generated |
| Requester | The person or agent requesting the service |
| Resolver | The context-sensitive service that processes the OpenURL |
| ServiceType | The type of service requested |
| ContextObject | The container for all transported metadata |
Key Metadata Elements
For journal articles, the most commonly transported metadata keys include:
| Key | Description |
|---|---|
rft.atitle |
Article title |
rft.jtitle |
Journal title |
rft.issn |
ISSN |
rft.volume |
Volume number |
rft.issue |
Issue number |
rft.spage |
Start page |
rft.date |
Publication date |
rft_id |
Identifier (e.g., DOI) |
COinS: OpenURL in HTML
A notable extension of OpenURL is COinS (ContextObject in SPAN), which embeds OpenURL metadata within HTML pages using empty <span> elements. This allows tools like Zotero to detect bibliographic references on web pages and import them into citation managers. COinS brought OpenURL beyond the library resolver context into general web-based scholarly communication.
Governance & Maintenance
The standard is maintained by the NISO OpenURL Standards Committee. It was reaffirmed in 2010 (Z39.88-2004 R2010). NISO manages the standard through its normal committee process, with public review periods for any proposed changes. The OpenURL Registry, originally hosted by OCLC, documents the community profiles and transport formats in use.
Notable Implementations
OpenURL is implemented by virtually every academic library that provides electronic resource access. Major link resolver products include Ex Libris SFX (now part of Alma), OCLC WorldCat Link Resolver, Serials Solutions 360 Link (now ProQuest), and EBSCO Full Text Finder. Citation databases such as Web of Science, Scopus, PubMed, and Google Scholar generate OpenURL links that connect to institutional resolvers. Discovery systems like Primo and Summon rely on OpenURL for full-text linking.
Related Standards
- DOI -- Digital Object Identifiers are frequently transported within OpenURL as
rft_idvalues - Z39.50 -- An earlier NISO standard for information retrieval that OpenURL partially supplanted for linking use cases