Serial Item and Contribution Identifier

The Serial Item and Contribution Identifier (SICI) was a code (ANSI/NISO standard Z39.56-1996 [R2002]) used to uniquely identify specific volumes, articles or other identifiable parts of a serial. It was "intended primarily for use by those members of the bibliographic community involved in the use or management of serial titles and their contributions". Developed over 1993-1995, NISO adopted SICI as a standard in 1996, then reaffirmed it in 2002. It was withdrawn in 2012.

It is an extension of the International Standard Serial Number, which identifies an entire serial (similar to the way an ISBN number identifies a specific book). The ISSN applies to the entire publication, however, including every volume ever printed, so this more specific identifier was developed by the Serials Industry Systems Advisory Committee (SISAC) to allow references to specific parts of a journal.

The variable-length, free of charge, code is compatible with other identifiers, such as DOI, PII and URN. Prior to January 2009, SICIs were valid DOI suffixes for registration at the Crossref registration agency. However, to accommodate a security problem with Microsoft's Internet Explorer, they decided that they would soon refuse to register DOI suffixes that contain the colon character.

The SICI is a recognized international standard and is in wide use by publishers and the bibliographic community, primarily as an aid to finding existing articles or issues. JSTOR adopted SICIs in 2001 as its primary article-level identifier and the core of its stable and citation-derivable URLs. SICI was selected over simpler alternatives because of its ability to encompass the many varieties of journal metadata found in JSTOR's archive. However, due to difficulties encountered by its partners in calculating the correct values for the title code and the check digit, JSTOR's implementation of the standard ignores those elements. JSTOR now recommends against using SICI, and instead strongly suggests using DOIs instead. This is also done because sometimes multiple articles on the same page have exactly the same name (in particular "Obituary").

The SICI code is composed of three segments, intended to be both human-readable and easy for machines to parse automatically. The following example SICI is explained below:

To use as an info URI, the SICI is percent-encoded and prefixed.

To use in a URN, the SICI is percent-encoded and prefixed. For example, to create a URN for a specific article "From text to hypertext by indexing" in the journal ACM Transactions on Information Systems:

This could then be used to refer to the article inside an HTML citation (in the element), for instance, in a way that is superior to an HTTP link for documents that are not on the web or have transient URLs:

A model is presented for converting a collection of documents to hypertext
by means of indexing. The documents are assumed to be semistructured, i.e.,
their text is a hierarchy of parts, and some of the parts consist of natural
language. The model is intended as a framework for specifying hypertextual
reading capabilities for specific application areas and for developing new
automated tools for the conversion of semistructured text to hypertext.

An Internet Draft proposal to officially register the SICI namespace for URNs with IANA was made in 2002, but is currently dormant.

SICI codes can be used as the item ID in a DOI identifier. In the following example, the number 10.1002 is the DOI's publisher ID, a slash acts as a separator, and the rest, which is publisher-specific, is the SICI code:

CrossRef no longer allows DOIs with colons to be registered, greatly reducing the usefulness of such SICIs.