ANSI/NISO Z39.56 (SICI — Serial Item and Contribution Identifier)

The Serial Item and Contribution Identifier (SICI) was an ANSI/NISO standard (Z39.56-1996 [R2002]) for encoding a machine-readable identifier for a specific volume, issue, or article within a serial publication — extending what an ISSN alone could identify (the continuing title, not a specific item within it). It was developed by the Serials Industry Systems Advisory Committee (SISAC) between 1993 and 1995, adopted as a NISO standard in 1996, reaffirmed in 2002, and formally withdrawn by NISO in 2012. A publication or system that still cites “SICI” today is almost always describing legacy infrastructure — new identifier assignment for serial articles has moved to the DOI.

Operational definition

A code counts as a SICI, in the ANSI/NISO Z39.56 sense, only if it is built from three defined segments in sequence:

• Item segment — the ISSN of the serial, its chronology (publication date), and its enumeration (volume/issue number).
• Contribution segment — the starting page location and a title-code checksum for the specific article, delimited by angle brackets.
• Control segment — a code-structure identifier, derivative-part identifier, format code, version number, and a trailing check character used to validate the whole string.

All three segments, assembled with the standard’s punctuation, are required — a bare ISSN or a partial fragment does not constitute a SICI.

Illustrative example

The general shape of a SICI string is:

1234-5678(19960101)47:1<3:ABCDE>2.0.TX;2-X

This is an illustrative pattern only, not a real journal article — it is shown to demonstrate the syntax, not to assert any specific publication. Reading left to right: 1234-5678 is the ISSN (item segment), (19960101) the chronology, 47:1 the volume/issue, the bracketed <3:ABCDE> the contribution segment (starting page and title code), and the trailing 2.0.TX;2-X the control segment.

Relationship to DOI

SICI codes were designed to be DOI-compatible — a SICI could historically be used as the suffix portion of a DOI (see DOI prefix and DOI suffix for how the two parts of a DOI are structured generally). In practice this combination saw limited real-world uptake, and Crossref stopped registering DOIs containing colon characters in 2009, which further narrowed where a SICI-as-suffix pattern could still work, since a SICI’s contribution segment uses a colon as a delimiter. Publishers and platforms that adopted SICI early — JSTOR is the most frequently cited example — have since moved to registering plain DOIs directly rather than SICI-derived ones. For CASRAI’s audience, the practical takeaway is historical: SICI represents an earlier, more complex approach to the same problem DOI later solved more simply — a stable, resolvable, machine-actionable identifier scheme for a specific piece of published content.

Not a SICI (counter-example)

An ISSN on its own, such as 0000-0000, is not a SICI — it identifies the serial title as a continuing resource, not any specific volume, issue, or article within it. Likewise, a modern article-level DOI such as 10.1038/nature12373 is not a SICI, even though it serves the equivalent identifying function today; DOIs use a registrant-assigned prefix/suffix structure (see DOI prefix) rather than the ISSN-plus-chronology-plus-checksum structure Z39.56 defined.

Why this matters for research administration today

SICI is relevant to CASRAI’s audience mainly as a legacy-data problem: institutional repositories, older library catalogs, and some pre-2010 publisher metadata may still carry SICI strings as an item-level identifier. When reconciling or migrating such records into a current identifier crosswalk alongside DOI, ORCID, and ROR, a SICI should generally be treated as a superseded identifier to be mapped forward to a DOI where one exists, not as an active identifier to keep minting. See the CASRAI guide on connecting DOI, ORCID, ROR, and institutional identifiers in practice for the broader crosswalk pattern this fits into.

Related terms and standards

• ISSN — the serial-title identifier a SICI’s item segment was built on top of.
• DOI — the persistent identifier scheme that has effectively superseded SICI for article-level identification.
• DOI prefix and DOI suffix — the structure of the identifier that replaced SICI in practice.
• Identifier scheme — the general concept SICI, ISSN, and DOI are all instances of.
• Identifier crosswalk — how legacy identifiers like SICI get mapped to current ones during data migration.
• NISO Institutional Identifier (I2) — another withdrawn/legacy NISO identifier standard, for institutions rather than serial content.
• ANSI/NISO Z39.19 (Controlled Vocabularies and Thesauri) — another NISO Z39.x standard relevant to scholarly publishing infrastructure.
• Persistent Identifier (PID) — the broader category; note SICI was not itself persistent/resolvable in the way a DOI is, which is part of why it did not last.