Editing ISSN

{{Short description|Serial number used to identify a periodical publication}}
{{Distinguish|ISBN}}
{{for|the use of ISSNs on Wikipedia|Wikipedia:ISSN|selfref=y}}
{{Infobox identifier
| name          = International Standard Serial Number
| image         = ISSN logo.svg
| image_caption = 
| image_class   = notheme
| image_style   = background-color: #f8f9fa;
| acronym       = ISSN
| start_date    = {{Start date and age|1976}}
| number        = > 2,500,000
| organisation  = ISSN International Centre
| digits        = 8
| check_digit   = Weighted sum
| example       = 2049-3630
| website       = {{URL|https://www.issn.org/}}
}}

[[File:Issn barcode.png|thumb|ISSN for ''[[Pilgrims of Saint Michael|Vers Domain]]'', encoded in an EAN-13 barcode with sequence variant 0 and issue number 05]]
[[File:Issn-barcode-explained.png|thumb|Example of an ISSN, 2049-3630, encoded in an [[International Article Number (EAN)|EAN-13 bar code]], with explanation]]
[[File:ISSN with addon EAN13.svg|thumb|ISSN expanded with sequence variant 0 to a [[Global Trade Item Number|GTIN-13]] and encoded in an [[EAN-13]] barcode with an [[EAN 2|EAN-2]] add-on designating issue number 13]]

An '''International Standard Serial Number''' ('''ISSN''') is an eight-digit to [[unique identifier|uniquely identify]] a [[serial (publishing)|periodical publication]] (periodical), such as a magazine.<ref name=Whatis>{{cite web |url=https://www.issn.org/understanding-the-issn/what-is-an-issn |title=What is an ISSN? |publisher=ISSN International Centre |place=Paris |access-date=13 July 2014 |archive-date=16 July 2014 |archive-url=https://web.archive.org/web/20140716113932/http://www.issn.org/understanding-the-issn/what-is-an-issn/ |url-status=live }}</ref> The ISSN is especially helpful in distinguishing between serials with the same title. ISSNs are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature.<ref>{{cite web |url=http://www.bl.uk/bibliographic/issn.html |title=Collection Metadata Standards |publisher=British Library |access-date=14 July 2014 |archive-date=15 July 2014 |archive-url=https://web.archive.org/web/20140715143822/http://www.bl.uk/bibliographic/issn.html |url-status=live }}</ref>

The ISSN system was first drafted as an [[International Organization for Standardization]] (ISO) [[international standard]] in 1971 and published as ISO 3297 in 1975.<ref>{{cite web |url=https://www.issn.org/understanding-the-issn/standardization |title=ISSN, a Standardised Code |publisher=ISSN International Centre |place=Paris |access-date=13 July 2014 |archive-date=16 July 2014 |archive-url=https://web.archive.org/web/20140716124242/http://www.issn.org/understanding-the-issn/standardization/ |url-status=live }}</ref> ISO subcommittee [[TC 46/SC 9]] is responsible for maintaining the standard.

When a serial with the same [[content (media)|content]] is published in more than one [[media (communication)|media type]], a different ISSN is assigned to each media type. For example, many serials are published both in [[Printing|print]] and [[electronic media]]. The ISSN system refers to these types as '''print ISSN''' ('''p-ISSN''') and '''electronic ISSN''' ('''e-ISSN''').<ref>{{Cite web|url=https://www.issn.org/understanding-the-issn/assignment-rules/the-issn-for-electronic-media/?lang=en|title=The ISSN for electronic media|last=ISSN InterNational Centre|website=ISSN|access-date=2020-04-03|archive-date=11 October 2017|archive-url=https://web.archive.org/web/20171011031921/http://www.issn.org/understanding-the-issn/assignment-rules/the-issn-for-electronic-media/?lang=en|url-status=live}}</ref> 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.<ref>{{Cite book |date=January 2015 |title=ISSN Manual |publisher=ISSN International Centre |place=Paris |url=https://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf |pages=14, 16, 55–58 |chapter=3 |access-date=22 October 2018 |archive-date=12 July 2020 |archive-url=https://web.archive.org/web/20200712102227/http://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf |url-status=dead }} [https://www.issn.org/understanding-the-issn/assignment-rules/issn-manual HTML version available at www.issn.org] {{Webarchive|url=https://web.archive.org/web/20181018185939/http://www.issn.org/understanding-the-issn/assignment-rules/issn-manual/ |date=18 October 2018 }}</ref>

== Code format ==
An ISSN is an eight-digit code, divided by a hyphen into two four-digit numbers.<ref name=Whatis /> The last digit, which may be zero through nine or an X, is a [[check digit]], so the ISSN is uniquely represented by its first seven digits. Formally, the general form of the ISSN (also named "ISSN structure" or "ISSN syntax") can be expressed as follows:{{Ref RFC|3044}}
{{block indent |left=2 |text= {{Code|NNNN-NNNC}} }}
where <code>N</code> is in the set {''0,1,2,...,9''}, a decimal digit character, and <code>C</code> is in {''0,1,2,...,9,X''}; or by a [[Perl Compatible Regular Expressions]] (PCRE) [[regular expression]]:
{{block indent |left=2 |text= {{Code|lang=perl|1=^[0-9]{4}-[0-9]{3}[0-9X]$}}. }}

For example, the ISSN of the journal ''[[Hearing Research]]'', is 0378-5955, where the final 5 is the check digit, that is <code>C</code>=5. To calculate the check digit, the following algorithm may be used:

{{block indent |left=2 |text= Each of the first seven digits of the ISSN is multiplied by its position in the number, counting from the right, that is, 8, 7, 6, 5, 4, 3, and 2, respectively, and the resulting products are added:
<math display=block>\begin{align}
&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\;.
\end{align}</math>

The [[remainder]] of this sum [[modulo]] 11 is then calculated:
<math display=block>\frac{160}{11} = 14\mbox{ remainder }6=14+\frac{6}{11}</math>

If there is no remainder, the check digit is 0; otherwise the remainder is subtracted from 11. If the result is less than 10, it yields the check digit:
<math display=block>11 - 6 = 5\;.</math>
Thus, in this example, the check digit <code>C</code> is 5.

If the result is 10 (that is, if the remainder is 1), the check digit is an uppercase X (like a [[Roman numerals|Roman ten]]).
}} <!-- end long block indent -->

To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by their position in the number, counting from the right. (If the check digit is X, add 10 to the sum.) The remainder of the sum modulo 11 must be 0. There is an online ISSN checker that can validate an ISSN, based on the above algorithm.<ref>{{cite web |url=https://journal-index.org/index.php/issnChecker|title=Online ISSN Validator |publisher=Advanced Science Index |access-date=16 Sep 2023 |archive-date=2 Aug 2023 |archive-url=https://web.archive.org/web/20230802120549/https://journal-index.org/index.php/issnChecker |url-status=live }}</ref>

=== In EANs ===

ISSNs can be encoded in [[International Article Number (EAN)|EAN-13 bar codes]] with a 977 "country code" (compare the 978 "[[bookland]]" country code for [[ISBN]]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 (in most cases, this will not match the ISSN check digit, since they are each calculated in a different way).<ref>{{cite book|url=https://www.issn.org/understanding-the-issn/issn-uses/identification-with-the-ean-13-barcode/|title=Identification with the GTIN 13 barcode|publisher=ISSN International Centre|archive-url=https://web.archive.org/web/20200629062603/https://www.issn.org/understanding-the-issn/issn-uses/identification-with-the-ean-13-barcode/|archive-date=June 29, 2020|url-status=live}}</ref>

== Code assignment, maintenance and look-up ==
<!--Currently, "ISSN International Centre" redirects to this section, though it is a redirect with possibilities.-->
ISSN codes are assigned by a network of ISSN National Centres, usually located at [[national library|national libraries]] and coordinated by the '''ISSN International Centre''' based in [[Paris]]. The International Centre is an [[intergovernmental organization]] created in 1974 through an agreement between [[UNESCO]] and the French government.

=== Linking ISSN ===
''ISSN-L'' is a [[unique identifier]] for all versions of the serial containing the same [[content (media)|content]] 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;<ref>{{cite web |author= |title=Linking ISSN (ISSN-L) |url=http://www.nationallibrary.fi/publishers/issn/issnl.html |url-status=dead |archive-url=https://web.archive.org/web/20150926075657/http://www.nationallibrary.fi/publishers/issn/issnl.html |archive-date=26 September 2015 |access-date=23 December 2018 |website=www.nationallibrary.fi}}</ref> 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]], [[library catalogue]]s, [[search engine]]s or [[knowledge base]]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''. {{As of|2016|12|31|alt=At the end of 2016,}} the ISSN Register contained records for 1,943,572 items.<ref>{{cite web |title=Total number of records in the ISSN Register |url=https://www.issn.org/wp-content/uploads/2017/02/Total-records-in-Register.pdf |publisher=ISSN International Centre |access-date=23 February 2017 |date=February 2017 |archive-date=24 February 2017 |archive-url=https://web.archive.org/web/20170224055145/http://www.issn.org/wp-content/uploads/2017/02/Total-records-in-Register.pdf |url-status=live }}</ref> 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]] 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 "{{code|https://www.worldcat.org/ISSN/}}", e.g. [https://www.worldcat.org/ISSN/1021-9749 n2:1021-9749 – Search Results]. This does not query the ISSN Register itself, but rather shows whether any WorldCat library holds an item with the given ISSN.
<!-- Though an [https://www.issn.org:8080/English/pub/faqs/issn/issnchecking ISSN checking facility] {{Dead link|date=July 2022}} is available, this is a tool for checking the validity of an ISSN number format, not for querying the ISSN Register to determine what serial the input number is associated with. -->

== Comparison with other identifiers ==
ISSN and [[ISBN]] codes are similar in concept, where ISBNs are assigned to individual [[book]]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]] as to the [[publisher]] or its [[location (geography)|location]]. 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, 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]]): the [[Publisher Item Identifier]] (PII) and the [[Serial Item and Contribution Identifier]] (SICI).

=== Media versus content <span class="anchor" id="CD ISSN"></span>===
Separate ISSNs are needed for serials in different media (except reproduction [[microform]]s). Thus, the [[print media|print]] and [[electronic media]] versions of a serial need separate ISSNs,<ref>{{cite web |url=https://www.loc.gov/issn/e-serials.html |title=ISSN for Electronic Serials |date=19 February 2010 |publisher=U.S. ISSN Center, Library of Congress |access-date=12 July 2014 |archive-date=17 February 2014 |archive-url=https://web.archive.org/web/20140217153904/http://www.loc.gov/issn/e-serials.html |url-status=live }}</ref> and [[CD-ROM]] versions and [[World Wide Web|web]] versions require different ISSNs. However, the same ISSN can be used for different file formats (e.g. [[PDF]] and [[HTML]]) 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 [[excess demand|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]] and its application, the [[digital object identifier]] (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".<ref name="issnL">{{cite web |url=https://www.issn.org/understanding-the-issn/assignment-rules/the-issn-l-for-publications-on-multiple-media/ |title=The ISSN-L for publications on multiple media |publisher=ISSN International Centre |access-date=12 July 2014 |archive-date=16 July 2014 |archive-url=https://web.archive.org/web/20140716124227/http://www.issn.org/understanding-the-issn/assignment-rules/the-issn-l-for-publications-on-multiple-media/ |url-status=live }}</ref>

== Use in URNs ==
An ISSN can be encoded as a [[uniform resource name]] (URN) by prefixing it with "{{code|urn:ISSN:}}".{{Ref RFC|3044}} For example, [[Rail (magazine)|''Rail'']] could be referred to as "{{code|urn:ISSN:0953-4563}}". URN namespaces are case-sensitive, and the ISSN namespace is all caps.<ref>{{cite web|url=http://dublincore.org/architecturewiki/ResourceIdentifierGuidelines#head-a2100b457f3211cf98e960a3a481007893c4e68a |archive-url=https://web.archive.org/web/20120513221344/http://dublincore.org/architecturewiki/ResourceIdentifierGuidelines |archive-date=13 May 2012 |title=Guidelines for using resource identifiers in Dublin Core metadata §4.5&nbsp;ISSN |last1=Powell |first1=Andy |last2=Johnston |first2=Pete |last3=Campbell |first3=Lorna |last4=Barker |first4=Phil |date=21 June 2006 |website=Dublin Core Architecture Wiki |url-status=dead }}</ref> If the checksum digit is "X" then it is always encoded in uppercase in a URN.

=== Problems ===
The URNs are [[#Media versus content|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 (journal)|Nature]] 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]]. As the ISSN is not unique, the [[U.S. National Library of Medicine]] needed to create, prior to 2007, the NLM Unique ID (JID).<ref>{{cite web |url=https://www.nlm.nih.gov/bsd/mms/medlineelements.html#jid |title=MEDLINE/PubMed Data Element (Field) Descriptions |date=7 May 2014 |publisher=U.S. National Library of Medicine |access-date=19 July 2014 |archive-date=27 April 2019 |archive-url=https://web.archive.org/web/20190427130927/https://www.nlm.nih.gov/bsd/mms/medlineelements.html#jid |url-status=live }}</ref>
* '''ISSN''' does not offer [[uniform resource name#Resolvers|resolution mechanisms]] like a [[digital object identifier]] (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 <code>''<nowiki>https://doi.org/</nowiki>''10.1038/nature13777</code>, and is [[URL redirection|redirected]] (resolved) to the current article's page; but there is no ISSN online service, like <code><nowiki>http://dx.issn.org/</nowiki></code>, to resolve the ISSN of the journal (in this sample [[Nature (journal)|1476-4687]]).

A unique URN for serials simplifies the search, recovery and delivery of data for various services including, in particular, [[information retrieval|search systems]] and [[knowledge base|knowledge databases]].<ref name="issnL" /> '''ISSN-L''' (see [[#Linking ISSN|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]] contexts (e.g., [[JATS]]), these may have standard labels.

=== Print ISSN ===
''p-ISSN'' is a standard label for "Print ISSN", the ISSN for the [[print media]] (paper) version of a serial. Usually it is the "default media" and so the "default ISSN".

=== Electronic ISSN <span class="anchor" id="eISSN"></span>===
''e-ISSN'' (or ''eISSN'') is a standard label for "Electronic ISSN", the ISSN for the [[electronic media]] (online) version of a serial.<ref>"La nueva Norma ISSN facilita la vida de la comunidad de las publicaciones en serie", A. Roucolle. {{cite web |url=http://www.latindex.unam.mx/biblioteca/nunoiso.html |title=La nueva norma ISSN |access-date=2014-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20141210063334/http://www.latindex.unam.mx/biblioteca/nunoiso.html |archive-date=10 December 2014 |df=dmy-all }}</ref>

== ROAD <!--section with possibility-->==
* {{interlanguage link|ROAD: Directory of Open Access Scholarly Resources|it|Directory of Open Access Scholarly Resources}} (est. 2013), produced by the [[ISSN International Centre]] and [[UNESCO]]<ref>{{cite web |url=http://road.issn.org/en |title=Road in a nutshell |website=Road.issn.org |access-date=12 September 2017 |archive-url=https://web.archive.org/web/20170905182813/http://road.issn.org/en |archive-date=5 September 2017 |url-status=dead |df=dmy-all }}</ref>

== See also ==
* [[CODEN]]
* [[WorldCat]]—an ISSN-resolve service

== References ==
{{Reflist|30em}}

== External links ==
{{sisterlinks|d=Q131276|c=Category:ISSN|n=no|b=no|q=no|v=no|voy=no|m=no|mw=no|s=no|wikt=no|species=ISSN}}
{{Wikidata property|P236}}
* [https://www.issn.org/ ISSN International Centre]
* [https://portal.issn.org/ ISSN Portal]
* [https://docs.google.com/spreadsheet/ccc?key=0AusE0e8tdNZVdDFHRnVEZmNCQ3NSNGxNamxDMk44a1E List of 63800 ISSN numbers and titles]
* {{Citation|edition=2015|place=Paris|publisher=ISSN InterNational Centre|date=January 2015|url=https://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf|last=ISSN InterNational Centre|title=ISSN Manual|postscript=.|access-date=22 October 2018|archive-date=12 July 2020|archive-url=https://web.archive.org/web/20200712102227/http://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf|url-status=dead}}
* {{Citation |place=United States |publisher=Library of Congress |url=https://www.loc.gov/issn/issnbro.html |title=How U.S. publishers can obtain an ISSN}}.
* {{Citation |place=Ottawa|publisher=[[Library and Archives Canada]] |access-date=2020-04-03|date=2020-01-08|url=http://www.bac-lac.gc.ca/eng/services/issn-canada/Pages/issn-canada.aspx |postscript=.|title=ISSN Canada |last1=Canada |first1=Library Archives }}.
* {{Citation |publisher=British Library |url=http://www.bl.uk/bibliographic/issn.html |title=Getting an ISSN in the UK |access-date=8 October 2008 |archive-date=15 July 2014 |archive-url=https://web.archive.org/web/20140715143822/http://www.bl.uk/bibliographic/issn.html |url-status=dead }}.
* {{Citation |publisher=Bibliothèque nationale de France |url=http://www.bnf.fr/fr/professionnels/s_informer_obtenir_issn/s.obtenir_issn.html?first_Art=non |title=Getting an ISSN in France | date=15 June 2023 |language=fr}}
* {{Citation |publisher=Deutsche Nationalbibliothek |url=http://www.dnb.de/DE/Wir/Kooperation/ISSN/issnFAQ.html |title=Getting an ISSN in Germany |language=de |access-date=8 March 2012 |archive-date=11 December 2017 |archive-url=https://web.archive.org/web/20171211053445/http://www.dnb.de/DE/Wir/Kooperation/ISSN/issnFAQ.html |url-status=dead }}
* {{Citation |publisher=National Library of South Africa |url=http://www.nlsa.ac.za/index.php/bibsa/isn-agency |title=Getting an ISSN in South Africa |access-date=7 January 2015 |archive-url=https://web.archive.org/web/20171224193322/http://www.nlsa.ac.za/index.php/bibsa/isn-agency |archive-date=24 December 2017 |url-status=dead }}

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{{Use dmy dates|date=August 2017}}

[[Category:Computer-related introductions in 1976]]
[[Category:Checksum algorithms]]
[[Category:ISO standards]]
[[Category:Library science]]
[[Category:Serial numbers]]
[[Category:Unique identifiers]]