The ISSN is defined by ISO 3297

The ISSN is defined by a specific standard; is, that is, the subject of defining and implementing standardized rules, internationally adopted under the ISO (International Organization for Standardization), an institution that brings together official organizations for standardization around the world. From this it is derived, at the international level, a generalized use of the system, consistent and compatible. The competent authority for the registration of the ISSN, recognized by ISO, is the ISSN International Centre.

The other identification codes

The principle of an identification code for international standard exists in many areas. Monographs for example are identified by ISBN (International Standard Book Number), musical scores by ISMN (International Standard Music Number), sound recordings by ISRC (International Standard Recording Code), etc. Each of these codes refers to a specific and well-defined field of application and to a logic connected to it. As regards the ISSN, it should be noted that its application extends, among other things, also to the series of books; a monograph which is part of a collection, in fact, may have both an ISSN (which identifies the necklace), and an ISBN (that identifies the individual monograph, within the collection).

The ISSN and SICI code

The ISSN is the fundamental element of a code of great importance for the identification of issues and journal articles: the SICI (Serial Item and Contribution Identifier) which is described by the American standard ANSI / NISO (Z39.56). The code SICI, whose use among the great international scientific publishers, agencies that manage reproduction rights, etc. is becoming ever more common, allows you to unambiguously identify each item (or contribution) contained in any given issue of a serial publication.

The representation of the SICI (at issue level) and its bar code, readable by a scanner, is known under the name of "SISAC Bar code Symbol" (Simbolo SISAC  del codice a barre). At present, the industry of serial publications, as well as the publishers of major international importance, either equip their publications of "SISAC Bar code Symbol"; likewise, on the same basis, the producers of library management systems invent interfaces for automatic control of issues.

The SISAC barcode  contains all the elements of SICI, but formats them in a slightly different way to get a full numeric code that allows a reduction of the length of the barcode symbology 128.

Here's an example of SICI code  (which identifies a particular issue of a serial publication) and of the equivalent barcode equivalent (SISAC barcode ).

The SICI, which is located under the bar code, contains:
1. the ISSN,
2. the date of publication, in brackets, and presented in the form YYYYMMDD (in this case 199303 for March 1993),
3. the number of issue (in this case 52),
4. the version number of the rule, in this case 1, preceded by a semicolon,
5. and finally a dash before the control font calculated according to the fonts that precede it.
It should be remembered that SISAC is the acronym for Serials Industry Systems Advisory Committee (Advisory Committee on systems designed for industrial serial publications), an organization created in 1982 in the United States for the development of standardized exchange formats for the management of serial publications (with emphasis on the relationships between libraries, subscription agents and publishers).