ContextObjects in Spans, commonly abbreviated COinS, is a method to embed bibliographic metadata in the HTML code of web pages. This allows bibliographic software to publish machine-readable bibliographic items and client reference management software to retrieve bibliographic metadata. The metadata can also be sent to an OpenURL resolver. This allows, for instance, searching for a copy of a book in one's own library.
In the late 1990s OpenURL was created at Ghent University as framework to provide context-sensitive links. The OpenURL link server implementation called SFX was sold to Ex Libris Group which marketed it to libraries, shaping the idea of a "link resolver". The OpenURL framework was later standardized as ANSI/NISO Z39.88 in 2004. A core part of OpenURL was the concept of "ContextObjects" as metadata to describe referenced resources.
In late 2004 Richard Cameron, the creator of CiteULike, drew attention to the need for a standard way of embedding metadata in HTML pages. Daniel Chudnov suggested the use of OpenURL. Embedding OpenURL ContextObjects in HTML had been proposed before by Herbert Van de Sompel and Oren Beit-Arie and a working paper by Chudnov and Jeremy Frumkin. Discussion of the latter on the GPS-PCS mailing list resulted in a draft specification for embedding OpenURLs in HTML, which later became COinS. A ContextObject is embedded in an HTML span element.
The adoption of COinS was pushed by various publications and implementations. The specification can now be found at http://ocoins.info/, which includes specific guides to implement COinS for journal articles and books and a COinS generator.
Summary of the data model 
From OpenURL 1.0 COinS borrows one of its serialization formats ("KEV") and some ContextObject metadata formats included in OpenURL implementation guidelines. The ContextObject implementation guidelines of COinS include four publication types (article with several subtypes, book, patent, and generic) and a couple of simple fields. However the guidelines are not required part of COinS, so the standard does not provide a strict metadata model like Dublin Core or the Bibliographic Ontology.
Use in web sites 
The following web sites make use of COinS:
Server-side applications 
Several server-side applications embed COinS:
Client tools 
Client tools which can use COinS include:
See also 
- Chudnov, Daniel (2006-07). "COinS for the Link Trail". Library Journal: 8–10.
- ANSI/NISO Z39.88 - The OpenURL Framework for Context-Sensitive Services. 2004. ISBN 978-1-880124-61-1.
- "Autodiscovery and embedding metadata". gcs-pcs-list. 2004-12-20. Retrieved 20 March 2011.
- "sample inline openurl". gcs-pcs-list. 2005-01-06. Retrieved 20 March 2011.
- Van de Sompel, Herbert; Beit-Arie, Oren (July/August 2001). "Generalizing the OpenURL Framework beyond References to Scholarly Works - The Bison-Futé Model". D-Lib 7 (7/8). doi:10.1045/july2001-vandesompel. ISSN 1082-9873.
- "GCS-PCS mailing list". Groups.google.com. Retrieved 2010-06-07.
- "Latent OpenURLs in HTML for Resource Autodiscovery, Localization and Personalization". Retrieved 20 March 2011.
- Apps, Ann (2003-04-16). "Z39.88-2004 KEV Implementation Guidelines". Retrieved 20 March 2011.
- "Mendeley Web now supports COinS". 2009-08-06. Retrieved 2009-08-06.
- Peter Binkley's plugin, described further in this post, can be used to refer to external sources within a WordPress post
- ScholarPress Coins plugin generates self-referential COinS for each WordPress post
- John Miedema's plugin creates COinS for books referenced in WordPress posts