Editing ISSN (section)

=== 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>