TheInfoList

An International Standard Serial Number (ISSN) is an eight-digit
serial number A serial number is a unique identifier A unique identifier (UID) is an identifier that is guaranteed to be unique among all identifiers used for those objects and for a specific purpose. The concept was formalized early in the development o ...

used to uniquely identify a
serial publication In publishing and library science, library and information science, the term serial is applied to materials "in any medium issued under the same title in a succession of discrete parts, usually numbered (or dated) and appearing at regular or irreg ...
, such as a magazine. The ISSN is especially helpful in distinguishing between serials with the same title. ISSNs is used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an
International Organization for Standardization The International Organization for Standardization (ISO ) is an international standard An international standard is a technical standard A technical standard is an established norm Norm, the Norm or NORM may refer to: In academic discipline ...
(ISO)
international standard An international standard is a technical standard A technical standard is an established norm Norm, the Norm or NORM may refer to: In academic disciplines * Norm (geology), an estimate of the idealised mineral content of a rock * Norm (philoso ...
in 1971 and published as ISO 3297 in 1975. ISO subcommittee
TC 46/SC 9ISO/TC 46 is Technical Committee 46 of the International Organization for Standardization (ISO), responsible for Information and documentation. Overview The scope of the committee is 'standardization of practices relating to libraries, documentati ...
is responsible for maintaining the standard. When a serial with the same
content Content or contents may refer to: Media * Content (media), information or experience provided to audience or end-users by publishers or media producers ** Content industry, an umbrella term that encompasses companies owning and providing mass m ...
is published in more than one
media type A media type (formerly known as MIME type) is a two-part identifier for file formats and format contents transmitted on the Internet. The Internet Assigned Numbers Authority, Internet Assigned Numbers Authority (IANA) is the official authority for ...
, a different ISSN is assigned to each media type. For example, many serials are published both in and
electronic media Electronic media are media Media may refer to: Physical means Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Br ...
. The ISSN system refers to these types as print ISSN (p-ISSN) and electronic ISSN (e-ISSN), respectively. Consequently, as defined in ISO 3297:2007, every serial in the ISSN system is also assigned a linking ISSN (ISSN-L), typically the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.

Code format

The format of the ISSN is an eight-digit code, divided by a hyphen into two four-digit numbers. As an
integer number An integer (from the Latin wikt:integer#Latin, ''integer'' meaning "whole") is colloquially defined as a number that can be written without a Fraction (mathematics), fractional component. For example, 21, 4, 0, and −2048 are integers, while ...
, it can be represented by the first seven digits. The last code digit, which may be 0-9 or an X, is a
check digit A check digit is a form of redundancy check used for error detection In information theory Information theory is the scientific study of the quantification, storage, and communication Communication (from Latin ''communicare'', meanin ...
. Formally, the general form of the ISSN code (also named "ISSN structure" or "ISSN syntax") can be expressed as follows: : : where N is in the set , a digit character, and C is in ; or by a
Perl Compatible Regular Expressions Perl Compatible Regular Expressions (PCRE) is a library A library is a curated collection of sources of information and similar resources, made accessible to a defined community for reference or borrowing. It provides physical or electronic ...
(PCRE)
regular expression A regular expression (shortened as regex or regexp; also referred to as rational expression) is a sequence of Character (computing), characters that specifies a ''search pattern matching, pattern''. Usually such patterns are used by string-se ...
: : . The ISSN of the journal ''Hearing Research'', for example, is 0378-5955, where the final 5 is the check digit, that is C=5. To calculate the check digit, the following algorithm may be used: :Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, and 2, respectively: ::$0\cdot 8 + 3\cdot 7 + 7\cdot 6 + 8\cdot 5 + 5\cdot 4 + 9\cdot 3 + 5\cdot 2$ ::$= 0 + 21 + 42 + 40 + 20 + 27 + 10$ ::$= 160$ :The modulus 11 of this sum is then calculated; divide the sum by 11 and determine the remainder: ::$\frac = 14\mbox6=14+\frac$ :If there is no remainder the check digit is 0, otherwise the remainder value is subtracted from 11 to give the check digit: ::$11 - 6 = 5$ :5 is the check digit, C. :For calculations, an upper case X in the check digit position indicates a check digit of 10 (like a Roman ten). To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right (if the check digit is X, then add 10 to the sum). The modulus 11 of the sum must be 0. There is an online ISSN checker that can validate an ISSN, based on the above algorithm.

In EANs

ISSNs can be encoded in EAN-13 bar codes with a 977 "country code" (compare the 978 country code ("
bookland "Bookland" is the informal name for the Unique Country Code (UCC) prefix allocated in the 1980s for European Article Number (EAN) identifiers of published book A book is a medium for recording information Information can be thought of ...
") for s), followed by the 7 main digits of the ISSN (the check digit is not included), followed by 2 publisher-defined digits, followed by the EAN check digit (which need not match the ISSN check digit).

Code assignment, maintenance and look-up

ISSN codes are assigned by a network of ISSN National Centres, usually located at
national libraries A national library is a library established by a government as a country's preeminent repository of information. Unlike public library, public libraries, these rarely allow citizens to borrow books. Often, they include numerous rare, valuable, or ...

and coordinated by the ISSN International Centre based in
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,175,601 residents , in an area of more than . Since the 17th century, Paris ha ...

. The International Centre is an
intergovernmental organization An intergovernmental organization (IGO) is an organization composed primarily of sovereign states (referred to as ''member states''), or of other organizations through formal treaties for handling/serving common interests and governed by interna ...
created in 1974 through an agreement between
UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO) (french: Organisation des Nations unies pour l'éducation, la science et la culture) is a specialised agency United Nations Specialized Agencies are autonomous orga ...

and the French government.

''ISSN-L'' is a
unique identifier A unique identifier (UID) is an identifier An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of objects, where the "object" or class may be an idea, physical countable In math ...
for all versions of the serial containing the same
content Content or contents may refer to: Media * Content (media), information or experience provided to audience or end-users by publishers or media producers ** Content industry, an umbrella term that encompasses companies owning and providing mass m ...
across different media. As defined by ''ISO 3297:2007'', the "linking ISSN (ISSN-L)" provides a mechanism for collocation or linking among the different media versions of the same continuing resource. The ''ISSN-L'' is one of a serial's existing ISSNs, so does not change the use or assignment of "ordinary" ISSNs; it is based on the ISSN of the first published medium version of the publication. If the print and online versions of the publication are published at the same time, the ISSN of the print version is chosen as the basis of the ''ISSN-L''. With ''ISSN-L'' is possible to designate one single ISSN for all those media versions of the title. The use of ''ISSN-L'' facilitates search, retrieval and delivery across all media versions for services like
OpenURL An OpenURL is similar to a web address, but instead of referring to a physical website, it refers to an article, book, patent, or other resource within a website. OpenURLs are similar to permalinks A permalink or permanent link is a Uniform Res ...
,
library catalogue A library catalog (or library catalogue in British English British English (BrE) is the standard dialect of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon E ...
s,
search engine A search engine is a software system A software system is a system of intercommunicating software component, components based on forming part of a computer system (a combination of Computer hardware, hardware and software). It "consists of a n ...
s or
knowledge base A knowledge base (KB) is a technology used to information storage, store complex structured data, structured and unstructured information used by a computer system. The initial use of the term was in connection with expert systems; which were the ...
s.

Register

The International Centre maintains a database of all ISSNs assigned worldwide, the ''ISDS Register'' (International Serials Data System), otherwise known as the ''ISSN Register''. the ISSN Register contained records for 1,943,572 items. The Register is not freely available for interrogation on the web, but is available by subscription. * The print version of a serial typically will include the ISSN code as part of the publication information. * Most serial websites contain ISSN code information. * Derivative lists of publications will often contain ISSN codes; these can be found through on-line searches with the ISSN code itself or serial title. *
WorldCat#REDIRECT WorldCat WorldCat is a union catalog that itemizes the collections of 15,600 libraries A library is a curated collection of sources of information and similar resources, made accessible to a defined community for reference or bo ...
permits searching its catalog by ISSN, by entering "issn:" before the code in the query field. One can also go directly to an ISSN's record by appending it to "", e.g. https://www.worldcat.org/ISSN/1021-9749. This does not query the ISSN Register itself, but rather shows whether any Worldcat library holds an item with the given ISSN.

Comparison with other identifiers

ISSN and codes are similar in concept, where ISBNs are assigned to individual
book A book is a medium for recording information Information is processed, organised and structured data Data (; ) are individual facts, statistics, or items of information, often numeric. In a more technical sense, data are a set of v ...

s. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no
information Information is processed, organised and structured data Data (; ) are individual facts A fact is something that is truth, true. The usual test for a statement of fact is verifiability—that is whether it can be demonstrated to c ...

as to the
publisher Publishing is the activity of making information, literature, music, software and other content available to the public for sale or for free. Traditionally, the term refers to the creation and distribution of printed works, such as book A ...

or its
location In geography Geography (from Ancient Greek, Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and phenomena of the Earth and Solar System, planets. Th ...
. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change.

Extensions

Since the ISSN applies to an entire serial a new identifier, other identifiers have been built on top of it to allow references to specific volumes, articles, or other identifiable components (like the
table of contents Table may refer to: * Table (information), a data arrangement with rows and columns * Table (furniture), a piece of furniture with a flat top and one or more legs * Table (database) * Calligra Tables, a spreadsheet application * Mathematical tab ...
): the
Publisher Item IdentifierThe Publisher Item Identifier (PII) is a unique identifier used by a number of scientific journal In academic publishing Academic publishing is the subfield of publishing Publishing is the activity of making information, literature, musi ...
(PII) and the
Serial Item and Contribution Identifier The Serial Item and Contribution Identifier (SICI) was a code (ANSI The American National Standards Institute (ANSI ) is a private non-profit organization A nonprofit organization (NPO), also known as a non-business entity, not-for-profit ...
(SICI).

Media versus content

Separate ISSNs are needed for serials in different media (except reproduction
microform Microforms are scaled-down reproductions of documents, typically either photographic film, films or paper, made for the purposes of transmission, storage, reading, and printing. Microform images are commonly reduced to about 4% or one twenty-fifth ...
s). Thus, the print and
electronic media Electronic media are media Media may refer to: Physical means Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Br ...
versions of a serial need separate ISSNs, and
CD-ROM A CD-ROM (, compact disc read-only memory) is a pre-pressed optical compact disc The compact disc (CD) is a digital Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardware *Digital ...

versions and
web Web most often refers to: * Spider web A spider web, spiderweb, spider's web, or cobweb (from the archaic word '' coppe'', meaning "spider") is a structure created by a spider Spiders ( order Araneae) are air-breathing arthropod An ar ...
versions require different ISSNs. However, the same ISSN can be used for different file formats (e.g.
PDF Portable Document Format (PDF), standardized as ISO 32000, is a file format ogg-file: 154 kilobytes. A file format is a standard Standard may refer to: Flags * Colours, standards and guidons * Standard (flag), a type of flag used for pe ...
and
HTML The HyperText Markup Language, or HTML is the standard markup language #REDIRECT Markup language In computer text processing, a markup language is a system for annotation, annotating a document in a way that is Syntax (logic), syntacticall ...

) of the same online serial. This "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, and the Web, it makes sense to consider only ''content'', independent of media. This "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the
indecs Content Model indecs (an acronym of "interoperability Interoperability is a characteristic of a product or system, whose interfaces are completely understood, to work with other products or systems, at present or in the future, in either implementation or a ...
and its application, the
digital object identifier#REDIRECT Digital object identifier {{Redirect category shell, 1= {{R from other capitalisation ...
(DOI), an ISSN-independent initiative, consolidated in the 2000s. Only later, in 2007, ISSN-L was defined in the new ISSN standard (ISO 3297:2007) as an "ISSN designated by the ISSN Network to enable collocation or versions of a continuing resource linking among the different media".

Use in URNs

An ISSN can be encoded as a
uniform resource name A Uniform Resource Name (URN) is a Uniform Resource Identifier A Uniform Resource Identifier (URI) is a unique sequence of characters that identifies a logical or physical resource used by web technologies. URIs may be used to identify anythin ...
(URN) by prefixing it with "". For example, ''Rail'' could be referred to as "". URN namespaces are case-sensitive, and the ISSN namespace is all caps. If the checksum digit is "X" then it is always encoded in uppercase in a URN.

Problems

The URNs are content-oriented, but ISSN is media-oriented: * ISSN is not unique when the concept is "a journal is a set of contents, generally copyrighted content": the same journal (same contents and same copyrights) may have two or more ISSN codes. A URN needs to point to "unique content" (a "unique journal" as a "set of contents" reference). :Example:
Nature Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including planets, stars, galaxy, galaxies, and all other forms of matter an ...
has an ISSN for print, 0028-0836, and another for the same content on the Web, 1476-4687; only the oldest (0028-0836) is used as a
unique identifier A unique identifier (UID) is an identifier An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of objects, where the "object" or class may be an idea, physical countable In math ...
. As the ISSN is not unique, the U.S. National Library of Medicine needed to create, prior to 2007, the NLM Unique ID (JID). * ISSN does not offer resolution mechanisms like a
digital object identifier#REDIRECT Digital object identifier {{Redirect category shell, 1= {{R from other capitalisation ...
(DOI) or a URN does, so the DOI is used as a URN for articles, with (for historical reasons) no need for an ISSN's existence. :Example: the DOI name "10.1038/nature13777" can be represented as an HTTP string by ''https://doi.org/''10.1038/nature13777, and is redirected (resolved) to the current article's page; but there is no ISSN online service, like http://dx.issn.org/, to resolve the ISSN of the journal (in this sample 1476-4687). A unique URN for serials simplifies the search, recovery and delivery of data for various services including, in particular, search systems and knowledge databases. ISSN-L (see Linking ISSN above) was created to fill this gap.

Media category labels

The two standard categories of media in which serials are most available are ''print'' and ''electronic''. In
metadata Metadata is "data Data (; ) are individual facts, statistics, or items of information, often numeric. In a more technical sense, data are a set of values of qualitative property, qualitative or quantity, quantitative variable (research), v ...

contexts (e.g.,
JATS The Journal Article Tag Suite (JATS) is an XML format used to Metadata, describe scientific literature published online. It is a technical standard developed by the National Information Standards Organization (NISO) and approved by the American N ...
), these may have standard labels.

Print ISSN

''p-ISSN'' is a standard label for "Print ISSN", the ISSN for the
print media Mass media refers to a diverse array of media technologies that reach a large audience via mass communication Mass communication is the process of imparting and exchanging information Information can be thought of as the resolution ...
(paper) version of a serial. Usually it is the "default media" and so the "default ISSN".

Electronic ISSN

''e-ISSN'' (or ''eISSN'') is a standard label for "Electronic ISSN", the ISSN for the
electronic media Electronic media are media Media may refer to: Physical means Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Br ...
(online) version of a serial.

* (est. 2013), produced by the ISSN International Centre and
UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO) (french: Organisation des Nations unies pour l'éducation, la science et la culture) is a specialised agency United Nations Specialized Agencies are autonomous orga ...

*
CODEN CODEN – according to ASTM standard E250 – is a six character, alphanumeric bibliographic code, that provides concise, unique and unambiguous identification of the titles of periodicals and non-serial publications from all subject areas. CODEN ...
*
WorldCat#REDIRECT WorldCat WorldCat is a union catalog that itemizes the collections of 15,600 libraries A library is a curated collection of sources of information and similar resources, made accessible to a defined community for reference or bo ...
—an ISSN-resolve service