Authority control In library science , authority control is a process that organizes library catalog and bibliographic information by using a single , distinct name for each topic . These one - of - a - kind headings are applied consistently throughout the catalog , and work with other organizing data such as linkages and cross references . Each heading is described briefly in terms of its scope and usage , and this organization helps the library staff maintain the catalog and make it user - friendly for researchers . The word " authority " in " authority control " derives from its initial use in identifying " authors " , and does not have the usual meaning of " authority " as a power relationship , although both senses of the word " authority " are related etymologically . Cataloguers assign each subject — such as an author , book , series or corporation — a particular unique heading term which is then used consistently , uniquely , and unambiguously to describe all references to that same subject , even if there are variations such as different spellings , pen name s , or alias es . The unique header can guide users to all relevant information including related or collocated subjects . Authority records can be combined into a database and called an " authority file " , and maintaining and updating these files as well as " logical linkages " to other files within them is the work of librarians and other information cataloguers . Accordingly , authority control is an example of controlled vocabulary and of bibliographic control . While in theory any piece of information is amenable to authority control such as personal and corporate names , uniform titles , series , and subjects , library cataloguers typically focus on author names and book titles . Subject headings from the Library of Congress fulfill a function similar to authority records , although they are usually considered separately . As time passes , information changes , prompting needs for reorganization . According to one view , authority control is not about creating a perfect seamless system but rather it is an ongoing effort to keep up with these changes and try to bring " structure and order " to the task of helping users find information . Examples . Differing names describe the same subject . Sometimes within a catalog there are different names or spellings for only one person or subject . This can bring confusion since researchers may miss some information . Authority control is used by cataloguers to collocate materials that logically belong together but which present themselves differently . Records are used to establish uniform title s which collocate all versions of a given work under one unique heading even when such versions are issued under different titles . With authority control , one unique preferred name represents all variations and will include different variations , spellings and misspellings , uppercase versus lowercase variants , differing dates , and so forth . For example , in Wikipedia , the subject of Princess Diana is described by an article Diana , Princess of Wales as well as numerous other descriptors , but both " Princess Diana " and " Diana , Princess of Wales " describe the same person ; an authority record would choose one title as the preferred one for consistency . In an online library catalog , various entries might look like the following : These different terms describe the same person . Accordingly , authority control reduces these entries to one unique entry or official authorized heading , sometimes termed an " access point " : Same name describes two different subjects . Sometimes two different authors have been published under the same name . This can happen if there is a title which is identical to another title or to a collective uniform title . This , too , can cause confusion . Different authors can be distinguished correctly from each other by , for example , adding a middle initial to one of the names ; in addition , other information can be added to one entry to clarify the subject , such as birth year , death year , range of active years such as 1918 – 1965 when the person flourished , or a brief descriptive epithet . When cataloguers come across different subjects with similar or identical headings , they can disambiguate them using authority control . Authority records and files . A customary way of enforcing authority control in a bibliographic catalog is to set up a separate index of authority records , which relates to and governs the headings used in the main catalog . This separate index is often referred to as an " authority file . " It contains an indexable record of all decisions made by cataloguers in a given library ( or — as is increasingly the case — cataloguing consortium ) , which cataloguers consult when making , or revising , decisions about headings . As a result , the records contain documentation about sources used to establish a particular preferred heading , and may contain information discovered while researching the heading which may be useful . While authority files provide information about a particular subject , their primary function is not to provide information but to organize it . They contain enough information to establish that a given author or title is unique , but that is all ; irrelevant but interesting information is generally excluded . Although practices vary internationally , authority records in the English - speaking world generally contain : For example , the Irish writer Brian O ' Nolan , who lived from 1911 to 1966 , wrote under many pen name s such as Flann O ' Brien and Myles na Gopaleen . Catalogers at the United States Library of Congress chose one form — " O ' Brien , Flann , 1911 – 1966 " — as the official heading . The example contains all three elements of a valid authority record : the first heading " O ' Brien , Flann , 1911 – 1966 " is the form of the name that the Library of Congress chose as authoritative . In theory , every record in the catalog that represents a work by this author should have this form of the name as its author heading . What follows immediately below the heading beginning with " Na Gopaleen , Myles , 1911 – 1966 " are the " see " references . These forms of the author ' s name will appear in the catalog , but only as transcriptions and not as headings . If a user queries the catalog under one of these variant forms of the author ' s name , he or she would receive the response : " See O ’ Brien , Flann , 1911 – 1966 . " There is an additional spelling variant of the Gopaleen name : " Na gCopaleen , Myles , 1911 – 1966 " has an extra C inserted because the author also employed the non - anglicized Irish spelling of his pen - name , in which the capitalized " C " shows the correct root word while the preceding " g " indicates its pronunciation in context . So if a library user comes across this spelling variant , he or she will be led to the same author regardless . " See also " references , which point from one authorized heading to another authorized heading , are exceedingly rare for personal name authority records , although they often appear in name authority records for corporate bodies . The final four entries in this record beginning with " His At Swim - Two - Birds . . . 1939 . " constitute the justification for this particular form of the name : it appeared in this form on the 1939 edition of the author ' s novel " At Swim - Two - Birds " , whereas the author ' s other " noms de plume " appeared on later publications . Access control . The act of choosing a single authorized heading to represent all forms of a name is often difficult , sometimes arbitrary and on occasion politically sensitive . An alternative is the idea of " access control " , where variant forms of a name are related without the endorsement of one particular form . Authority control and cooperative cataloging . Before the advent of digital Online public access catalog s and the Internet , creating and maintaining a library ' s authority files was generally carried out by individual cataloging departments within each library — that is , if such cataloguing was done at all . This often resulted in substantial disagreement between different libraries over which form of a given name was considered authoritative . As long as a library ' s catalog was internally consistent , differences between catalogs did not matter greatly . However , even before the Internet revolutionized the way libraries go about cataloging their materials , catalogers began moving toward the establishment of cooperative consortia , such as OCLC and RLIN in the United States , in which cataloging departments from libraries all over the world contributed their records to , and took their records from , a shared database . This development prompted to the need for national standards for authority work . In the United States , the primary organization for maintaining cataloging standards with respect to authority work operates under the aegis of the Library of Congress , and is known as the Name Authority Cooperative Program , or NACO Authority . Standards . There are various standards using different acronyms .