In academic publishing, a scientific journal is a periodical publication intended to further the progress of science by reporting new research. Articles in scientific journals are written by active scientists such as students and professors instead of professional journalists. There are thousands of scientific journals in publication, many more have been published at various points in the past. Most journals are specialized, although some of the oldest journals such as Nature publish articles and scientific papers across a wide range of scientific fields. Scientific journals contain articles that have been peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality, scientific validity. Although scientific journals are superficially similar to professional magazines, they are quite different. Issues of a scientific journal are read casually, as one would read a magazine; the publication of the results of research is an essential part of the scientific method. If they are describing experiments or calculations, they must supply enough details that an independent researcher could repeat the experiment or calculation to verify the results.
Each such journal article becomes part of the permanent scientific record. Articles in scientific journals can be used in higher education. Scientific articles allow researchers to keep up to date with the developments of their field and direct their own research. An essential part of a scientific article is citation of earlier work; the impact of articles and journals is assessed by counting citations. Some classes are devoted to the explication of classic articles, seminar classes can consist of the presentation by each student of a classic or current paper. Schoolbooks and textbooks have been written only on established topics, while the latest research and more obscure topics are only accessible through scientific articles. In a scientific research group or academic department it is usual for the content of current scientific journals to be discussed in journal clubs. Public funding bodies require the results to be published in scientific journals. Academic credentials for promotion into academic ranks are established in large part by the number and impact of scientific articles published.
Many doctoral programs allow for thesis by publication, where the candidate is required to publish a certain number of scientific articles. Articles tend to be technical, representing the latest theoretical research and experimental results in the field of science covered by the journal, they are incomprehensible to anyone except for researchers in the field and advanced students. In some subjects this is inevitable given the nature of the content. Rigorous rules of scientific writing are enforced by the editors. Articles are either original articles reporting new results or reviews of current literature. There are scientific publications that bridge the gap between articles and books by publishing thematic volumes of chapters from different authors. Many journals have a regional focus, specializing in publishing papers from a particular geographic region, like African Invertebrates; the history of scientific journals dates from 1665, when the French Journal des sçavans and the English Philosophical Transactions of the Royal Society first began systematically publishing research results.
Over a thousand ephemeral, were founded in the 18th century, the number has increased after that. Prior to mid-20th century, peer review was not always necessary, but it became compulsory; the authors of scientific articles are active researchers instead of journalists. As such, the authors receive no compensation from the journal. However, their funding bodies may require them to publish in scientific journals; the paper is submitted to the journal office, where the editor considers the paper for appropriateness, potential scientific impact and novelty. If the journal's editor considers the paper appropriate, the paper is submitted to scholarly peer review. Depending on the field and paper, the paper is sent to 1–3 reviewers for evaluation before they can be granted permission to publish. Reviewers are expected to check the paper for soundness of its scientific argument, i.e. if the data collected or considered in the paper support the conclusion offered. Novelty is key: existing work must be appropriately considered and referenced, new results improving on the state of the art presented.
Reviewers are unpaid and not a part of the journal staff—instead, they should be "peers", i.e. researchers in the same field as the paper in question. The standards that a journal uses to determine publication can vary widely; some journals, such as Nature, Science, PNAS, Physical Review Letters, have a reputation of publishing articles that mark a fundamental breakthrough in their respective fields. In many fields, a formal or informal hierarchy of scientific journals exists. In some countries, journal rankings can be utilized for funding decisions and evaluation of individual researchers, although they are poorly suited for that purpose. For scientific journals Reproducibility and Replicability are core concepts that allow other scientists to check and reproduce the results under the same conditions described
Outline of academic disciplines
An academic discipline or field of study is a branch of knowledge and researched as part of higher education. A scholar's discipline is defined by the university faculties and learned societies to which she or he belongs and the academic journals in which she or he publishes research. Disciplines vary between well-established ones that exist in all universities and have well-defined rosters of journals and conferences and nascent ones supported by only a few universities and publications. A discipline may have branches, these are called sub-disciplines. There is no consensus on how some academic disciplines should be classified, for example whether anthropology and linguistics are disciplines of the social sciences or of the humanities; the following outline is provided as topical guide to academic disciplines. Biblical studies Religious studies Biblical Hebrew, Biblical Greek, Aramaic Buddhist theology Christian theology Anglican theology Baptist theology Catholic theology Eastern Orthodox theology Protestant theology Hindu theology Jewish theology Muslim theology Biological anthropology Linguistic anthropology Cultural anthropology Social anthropology Archaeology Accounting Business management Finance Marketing Operations management Edaphology Environmental chemistry Environmental science Gemology Geochemistry Geodesy Physical geography Atmospheric science / Meteorology Biogeography / Phytogeography Climatology / Paleoclimatology / Palaeogeography Coastal geography / Oceanography Edaphology / Pedology or Soil science Geobiology Geology Geostatistics Glaciology Hydrology / Limnology / Hydrogeology Landscape ecology Quaternary science Geophysics Paleontology Paleobiology Paleoecology Astrobiology Astronomy Observational astronomy Gamma ray astronomy Infrared astronomy Microwave astronomy Optical astronomy Radio astronomy UV astronomy X-ray astronomy Astrophysics Gravitational astronomy Black holes Interstellar medium Numerical simulations Astrophysical plasma Galaxy formation and evolution High-energy astrophysics Hydrodynamics Magnetohydrodynamics Star formation Physical cosmology Stellar astrophysics Helioseismology Stellar evolution Stellar nucleosynthesis Planetary science Also a branch of electrical engineering Pure mathematics Applied mathematics Astrostatistics Biostatistics Academia Academic genealogy Curriculum Multidisciplinary approach Interdisciplinarity Transdisciplinarity Professions Classification of Instructional Programs Joint Academic Coding System List of fields of doctoral studies in the United States List of academic fields Abbott, Andrew.
Chaos of Disciplines. University of Chicago Press. ISBN 978-0-226-00101-2. Oleson, Alexandra; the Organization of knowledge in modern America, 1860-1920. ISBN 0-8018-2108-8. US Department of Education Institute of Education Sciences. Classification of Instructional Programs. National Center for Education Statistics. Classification of Instructional Programs: Developed by the U. S. Department of Education's National Center for Education Statistics to provide a taxonomic scheme that will support the accurate tracking and reporting of fields of study and program completions activity. Complete JACS from Higher Education Statistics Agency in the United Kingdom Australian and New Zealand Standard Research Classification Chapter 3 and Appendix 1: Fields of research classification. Fields of Knowledge, a zoomable map allowing the academic disciplines and sub-disciplines in this article be visualised. Sandoz, R. Interactive Historical Atlas of the Disciplines, University of Geneva
Astrophysics Data System
The Astrophysics Data System is an online database of over eight million astronomy and physics papers from both peer reviewed and non-peer reviewed sources. Abstracts are available free online for all articles, full scanned articles are available in Graphics Interchange Format and Portable Document Format for older articles, it was developed by the National Aeronautics and Space Administration, is managed by the Harvard–Smithsonian Center for Astrophysics. ADS is a powerful research tool and has had a significant impact on the efficiency of astronomical research since it was launched in 1992. Literature searches that would have taken days or weeks can now be carried out in seconds via the ADS search engine, custom-built for astronomical needs. Studies have found that the benefit to astronomy of the ADS is equivalent to several hundred million US dollars annually, the system is estimated to have tripled the readership of astronomical journals. Use of ADS is universal among astronomers worldwide, therefore ADS usage statistics can be used to analyze global trends in astronomical research.
These studies have revealed that the amount of research an astronomer carries out is related to the per capita gross domestic product of the country in which he/she is based, that the number of astronomers in a country is proportional to the GDP of that country, so the total amount of research done in a country is proportional to the square of its GDP divided by its population. For many years, a growing problem in astronomical research was that the number of papers published in the major astronomical journals was increasing meaning astronomers were able to read less and less of the latest research findings. During the 1980s, astronomers saw that the nascent technologies which formed the basis of the Internet could be used to build an electronic indexing system of astronomical research papers which would allow astronomers to keep abreast of a much greater range of research; the first suggestion of a database of journal paper abstracts was made at a conference on Astronomy from Large Data-bases held in Garching bei München in 1987.
Initial development of an electronic system for accessing astrophysical abstracts took place during the following two years. An initial version of ADS, with a database consisting of 40 papers, was created as a proof of concept in 1988, the ADS database was connected with the SIMBAD database in the summer of 1993; the creators believed this was the first use of the Internet to allow simultaneous querying of transatlantic scientific databases. Until 1994, the service was available via proprietary network software, but it was transferred to the nascent World Wide Web early that year; the number of users of the service quadrupled in the five weeks following the introduction of the ADS web-based service. At first, the journal articles available via ADS were scanned bitmaps created from the paper journals, but from 1995 onwards, the Astrophysical Journal began to publish an on-line edition, soon followed by the other main journals such as Astronomy and Astrophysics and the Monthly Notices of the Royal Astronomical Society.
ADS provided links to these electronic editions from their first appearance. Since about 1995, the number of ADS users has doubled every two years. ADS now has agreements with all astronomical journals, who supply abstracts. Scanned articles from as far back as the early 19th century are available via the service, which now contains over eight million documents; the service is distributed worldwide, with twelve mirror sites in twelve countries on five continents, with the database synchronized by means of weekly updates using rsync, a mirroring utility which allows updates to only the portions of the database which have changed. All updates are triggered centrally, but they initiate scripts at the mirror sites which "pull" updated data from the main ADS servers. Papers are indexed within the database by their bibliographic record, containing the details of the journal they were published in and various associated metadata, such as author lists and citations; this data was stored in ASCII format, but the limitations of this encouraged the database maintainers to migrate all records to an XML format in 2000.
Bibliographic records are now stored with sub-elements for the various metadata. Since the advent of online editions of journals, abstracts are loaded into the ADS on or before the publication date of articles, with the full journal text available to subscribers. Older articles have been scanned, an abstract is created using optical character recognition software. Scanned articles from before about 1995 are available free, by agreement with the journal publishers. Scanned articles are stored at both medium and high resolution; the TIFF files are converted on demand into GIF files for on-screen viewing, PDF or PostScript files for printing. The generated files are cached to eliminate needlessly frequent regenerations for popular articles; as of 2000, ADS contained 250 GB of scans, which consisted of 1,128,955 article pages comprising 138,789 articles. By 2005 this had grown to 650 GB, is expected to grow further, to about 900 GB by 2007. No further information has been published; the database contained only astronomical references, but has now grown to incorporate three databases, covering
OCLC Online Computer Library Center, Incorporated d/b/a OCLC is an American nonprofit cooperative organization "dedicated to the public purposes of furthering access to the world's information and reducing information costs". It was founded in 1967 as the Ohio College Library Center. OCLC and its member libraries cooperatively produce and maintain WorldCat, the largest online public access catalog in the world. OCLC is funded by the fees that libraries have to pay for its services. OCLC maintains the Dewey Decimal Classification system. OCLC began in 1967, as the Ohio College Library Center, through a collaboration of university presidents, vice presidents, library directors who wanted to create a cooperative computerized network for libraries in the state of Ohio; the group first met on July 5, 1967 on the campus of the Ohio State University to sign the articles of incorporation for the nonprofit organization, hired Frederick G. Kilgour, a former Yale University medical school librarian, to design the shared cataloging system.
Kilgour wished to merge the latest information storage and retrieval system of the time, the computer, with the oldest, the library. The plan was to merge the catalogs of Ohio libraries electronically through a computer network and database to streamline operations, control costs, increase efficiency in library management, bringing libraries together to cooperatively keep track of the world's information in order to best serve researchers and scholars; the first library to do online cataloging through OCLC was the Alden Library at Ohio University on August 26, 1971. This was the first online cataloging by any library worldwide. Membership in OCLC is based on use of services and contribution of data. Between 1967 and 1977, OCLC membership was limited to institutions in Ohio, but in 1978, a new governance structure was established that allowed institutions from other states to join. In 2002, the governance structure was again modified to accommodate participation from outside the United States.
As OCLC expanded services in the United States outside Ohio, it relied on establishing strategic partnerships with "networks", organizations that provided training and marketing services. By 2008, there were 15 independent United States regional service providers. OCLC networks played a key role in OCLC governance, with networks electing delegates to serve on the OCLC Members Council. During 2008, OCLC commissioned two studies to look at distribution channels. In early 2009, OCLC negotiated new contracts with the former networks and opened a centralized support center. OCLC provides bibliographic and full-text information to anyone. OCLC and its member libraries cooperatively produce and maintain WorldCat—the OCLC Online Union Catalog, the largest online public access catalog in the world. WorldCat has holding records from private libraries worldwide; the Open WorldCat program, launched in late 2003, exposed a subset of WorldCat records to Web users via popular Internet search and bookselling sites.
In October 2005, the OCLC technical staff began a wiki project, WikiD, allowing readers to add commentary and structured-field information associated with any WorldCat record. WikiD was phased out; the Online Computer Library Center acquired the trademark and copyrights associated with the Dewey Decimal Classification System when it bought Forest Press in 1988. A browser for books with their Dewey Decimal Classifications was available until July 2013; until August 2009, when it was sold to Backstage Library Works, OCLC owned a preservation microfilm and digitization operation called the OCLC Preservation Service Center, with its principal office in Bethlehem, Pennsylvania. The reference management service QuestionPoint provides libraries with tools to communicate with users; this around-the-clock reference service is provided by a cooperative of participating global libraries. Starting in 1971, OCLC produced catalog cards for members alongside its shared online catalog. OCLC commercially sells software, such as CONTENTdm for managing digital collections.
It offers the bibliographic discovery system WorldCat Discovery, which allows for library patrons to use a single search interface to access an institution's catalog, database subscriptions and more. OCLC has been conducting research for the library community for more than 30 years. In accordance with its mission, OCLC makes its research outcomes known through various publications; these publications, including journal articles, reports and presentations, are available through the organization's website. OCLC Publications – Research articles from various journals including Code4Lib Journal, OCLC Research, Reference & User Services Quarterly, College & Research Libraries News, Art Libraries Journal, National Education Association Newsletter; the most recent publications are displayed first, all archived resources, starting in 1970, are available. Membership Reports – A number of significant reports on topics ranging from virtual reference in libraries to perceptions about library funding. Newsletters – Current and archived newsletters for the library and archive community.
Presentations – Presentations from both guest speakers and OCLC research from conferences and other events. The presentations are organized into five categories: Conference presentations, Dewey presentations, Distinguished Seminar Series, Guest presentations, Research staff
University of Oxford
The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the world's second-oldest university in continuous operation, it grew from 1167 when Henry II banned English students from attending the University of Paris. After disputes between students and Oxford townsfolk in 1209, some academics fled north-east to Cambridge where they established what became the University of Cambridge; the two'ancient universities' are jointly called'Oxbridge'. The history and influence of the University of Oxford has made it one of the most prestigious universities in the world; the university is made up of 38 constituent colleges, a range of academic departments, which are organised into four divisions. All the colleges are self-governing institutions within the university, each controlling its own membership and with its own internal structure and activities, it does not have a main campus, its buildings and facilities are scattered throughout the city centre.
Undergraduate teaching at Oxford is organised around weekly tutorials at the colleges and halls, supported by classes, lectures and laboratory work provided by university faculties and departments. It operates the world's oldest university museum, as well as the largest university press in the world and the largest academic library system nationwide. In the fiscal year ending 31 July 2018, the university had a total income of £2.237 billion, of which £579.1 million was from research grants and contracts. The university is ranked first globally by the Times Higher Education World University Rankings as of 2019 and is ranked as among the world's top ten universities, it is ranked second in all major national league tables, behind Cambridge. Oxford has educated many notable alumni, including 27 prime ministers of the United Kingdom and many heads of state and government around the world; as of 2019, 69 Nobel Prize winners, 3 Fields Medalists, 6 Turing Award winners have studied, worked, or held visiting fellowships at the University of Oxford, while its alumni have won 160 Olympic medals.
Oxford is the home of numerous scholarships, including the Rhodes Scholarship, one of the oldest international graduate scholarship programmes. The University of Oxford has no known foundation date. Teaching at Oxford existed in some form as early as 1096, but it is unclear when a university came into being, it grew from 1167 when English students returned from the University of Paris. The historian Gerald of Wales lectured to such scholars in 1188 and the first known foreign scholar, Emo of Friesland, arrived in 1190; the head of the university had the title of chancellor from at least 1201, the masters were recognised as a universitas or corporation in 1231. The university was granted a royal charter in 1248 during the reign of King Henry III. After disputes between students and Oxford townsfolk in 1209, some academics fled from the violence to Cambridge forming the University of Cambridge; the students associated together on the basis of geographical origins, into two'nations', representing the North and the South.
In centuries, geographical origins continued to influence many students' affiliations when membership of a college or hall became customary in Oxford. In addition, members of many religious orders, including Dominicans, Franciscans and Augustinians, settled in Oxford in the mid-13th century, gained influence and maintained houses or halls for students. At about the same time, private benefactors established colleges as self-contained scholarly communities. Among the earliest such founders were William of Durham, who in 1249 endowed University College, John Balliol, father of a future King of Scots. Another founder, Walter de Merton, a Lord Chancellor of England and afterwards Bishop of Rochester, devised a series of regulations for college life. Thereafter, an increasing number of students lived in colleges rather than in halls and religious houses. In 1333–34, an attempt by some dissatisfied Oxford scholars to found a new university at Stamford, was blocked by the universities of Oxford and Cambridge petitioning King Edward III.
Thereafter, until the 1820s, no new universities were allowed to be founded in England in London. The new learning of the Renaissance influenced Oxford from the late 15th century onwards. Among university scholars of the period were William Grocyn, who contributed to the revival of Greek language studies, John Colet, the noted biblical scholar. With the English Reformation and the breaking of communion with the Roman Catholic Church, recusant scholars from Oxford fled to continental Europe, settling at the University of Douai; the method of teaching at Oxford was transformed from the medieval scholastic method to Renaissance education, although institutions associated with the university suffered losses of land and revenues. As a centre of learning and scholarship, Oxford's reputation declined in the Age of Enlightenment. In 1636 William Laud, the chancellor and Archbishop of Canterbury, codified the university's statutes. These, to a large extent, remained its gove
Chemical Abstracts Service
Chemical Abstracts Service is a division of the American Chemical Society. It is a source of chemical information. CAS is located in Columbus, United States. Chemical Abstracts is a periodical index that provides numerous tools such as SciFinder as well as tagged keywords, indexes of disclosures and structures of compounds in published scientific documents. 8,000 journals, technical reports, conference proceedings, new books, available in at least 50 different languages, are monitored yearly, as are patent specifications from 27 countries and two international organizations. Chemical Abstracts ceased print publication on January 1, 2010; the two principal databases that support the different products are Registry. CAplus consists of bibliographic information and abstracts for all articles in chemical journals worldwide, chemistry-related articles from all scientific journals and other scientific publications. Registry contains information on more than 130 million organic and inorganic substances, more than 64 million protein and Nucleic acid sequences.
The sequence information comes from GenBank, produced by the National Institutes of Health. The chemical information is produced by CAS, is prepared by the CAS Registry System, which identifies each compound with a specific CAS registry number, index name, graphic representation of its chemical structure; the assignment of chemical names is done according to the chemical nomenclature rules for CA index names, different from the internationally standard IUPAC names, according to the rules of IUPAC. CAS databases are available via two principal database systems, STN, SciFinder. STN International is operated jointly by CAS and FIZ Karlsruhe, is intended for information professionals, using a command language interface. In addition to CAS databases, STN provides access to many other databases, similar to Dialog. SciFinder is a database of chemical and bibliographic information. A client application, a web version was released in 2008, it has a graphics interface, can be searched for chemical structures and reactions as well as literature in chemistry and related disciplines.
The client version is for chemists in commercial organizations. Versions for both the Windows and Macintosh exist. SciFinder Scholar is for other academic institutions. CASSI stands for Chemical Abstracts Service Source Index. Since 2009, this print and CD-ROM compilation is available as a free online resource to look up and confirm publication information; the online CASSI Search Tool provides titles and abbreviations, CODEN, ISSN, date of first issue for a selected journal. Included is its language of text and language of summaries; the range is from 1907 to the present, including both serial and non-serial scientific and technical publications. The database is updated quarterly. Beyond CASSI lists abbreviated journal titles from early chemical literature and other historical reference sources. Chemical Abstracts developed from there; the use of volunteer abstractors was phased out in 1994. Chemical Abstracts has been associated with the American Chemical Society in one way or another since 1907.
For many years, beginning in 1909, the offices of Chemical Abstracts were housed in various places on the campus of Ohio State University in Columbus, Ohio. In 1965, CAS moved to a new 50-acre site on the west bank of the Olentangy River, just north of the Ohio State campus; this campus became well known in the Columbus area and famous as the site of many Columbus Symphony Orchestra pop concerts. In 2009, the campus consisted of three buildings. In 1907, William A. Noyes had enlarged the Review of American Chemical Research, an abstracting publication begun by Arthur Noyes in 1895, the forerunner of Chemical Abstracts; when it became evident that a separate publication containing these abstracts was needed, Noyes became the first editor of the new publication, Chemical Abstracts. E. J. Crane became the first Director of Chemical Abstracts Service when it became an American Chemical Society division in 1956. Crane had been CA editor since 1915, his dedication was a key factor in its long-term success.
Dale B. Baker became the CAS Director upon Crane's retirement in 1958. According to CAS, his visionary view of CAS' potential "led to expansion and the forging of international alliances with other information organizations." CAS was an early leader in the use of computer technology to disseminate information. The CAS Chemical Registry System was introduced in 1965. CAS developed a unique registry number to identify chemical substances. Agencies such as the U. S. Environmental Protection Agency and local fire departments around the world now rely on these numbers for the definite identification of substances. According to the ACS, this is the largest chemical substance database in the world. In 2007 the ACS designated its Chemical Abstracts Service subdivision an ACS National Historic Chemical Landmark in recognition of its significance as a comprehensive repository of research in chemistry and related sciences. Official website
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN 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.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, 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. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, 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, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. 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.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at 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. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. 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. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats 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, 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 and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the