Authority control
In library science, authority control is a process that organizes bibliographic information, for example in library catalogs by using a single, distinct spelling of a name (heading) or a numeric identifier for each topic. The word "authority" in "authority control" derives from the idea that the names of people, places, things, and concepts are "authorized," i.e., they are established in one particular form. These one-of-a-kind headings or identifiers are applied consistently throughout catalogs which make use of the respective authority file, and are applied for other methods of organizing data such as linkages and cross  references. Each controlled entry is described in an authority "record" in terms of its scope and usage, and this organization helps the library staff maintain the catalog and make it user-friendly for researchers. Catalogers assign each subject—such as author, topic, series, or corporation—a particular unique identifier or heading term which is then used consistently, uniquely, and unambiguously for all references to that same subject, which removes variations from different spellings, transliterations, pen names, or aliases. 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 catalogers. 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 names, and subjects, library catalogers typically focus on author names and titles of works. 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. Diverse names describe the same subject. Sometimes within a catalog, there are diverse names or spellings for only one person or subject. This variation may cause researchers to overlook relevant information. Authority control is used by catalogers to collocate materials that logically belong together but that present themselves differently . Records are used to establish uniform titles that 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 first wife of Charles, Prince of Wales is described by an article Diana, Princess of Wales as well as numerous other descriptors, e.g. Princess Diana, 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 terms describe the same person. Accordingly, authority control reduces these entries to one unique entry or officially authorized heading, sometimes termed an "access point": Diana, Princess of Wales, 1961–1997. Generally, there are different authority file headings and identifiers used by different libraries in different countries, possibly inviting confusion, but there are different approaches internationally to try to lessen the confusion. One international effort to prevent such confusion is the Virtual International Authority File which is a  collaborative attempt to provide a single heading for a particular subject. It is a way to standardize information from different authority files around the world such as the Integrated Authority File (GND) maintained and used cooperatively by many libraries in German-speaking countries and the United States Library of Congress. The idea is to create a single worldwide virtual authority file. For example, the ID for Princess Diana in the GND is "118525123" (preferred name: "Diana < Wales, Prinzessin>") while the United States Library of Congress uses the term "Diana, Princess of Wales, 1961–1997"; other authority files have other  choices. The Virtual International Authority File choice for all of these variations is "VIAF ID: 107032638" — that is, a common number representing all of these variations. The English Wikipedia prefers the term "Diana, Princess of Wales", but at the bottom of the article about her, there are links to various international cataloging efforts for reference purposes. 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 catalogers 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 catalogers in a given library (or—as is increasingly the case—cataloging consortium), which catalogers 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 the following information: For example, the Irish writer Brian O'Nolan, who lived from 1911 to 1966, wrote under many pen names 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 quite often a difficult and complex task, considering that any given individual may have legally  changed their name or used a variety of legal names in the course of their lifetime, as well as a variety of nicknames, pen names, stage names or other alternative names. It may be particularly difficult to choose a single authorized heading for individuals whose various names have controversial political or social connotations, when the choice of authorized heading may be seen as endorsement of the associated political or social ideology. An alternative to using authorized headings is the idea of "access control," where various forms of a name are related without the endorsement of one particular form. Cooperative cataloging . Before the advent of digital online public access catalogs and the Internet, creating and maintaining a library's authority files were generally carried out by individual cataloging departments within each library. Naturally, then, there was considerable difference in the authority files of the different libraries. For the early part of library history, it was generally accepted that, as long as a library's catalog was internally consistent, the differences between catalogs in different libraries did not matter greatly. As libraries became more attuned to the needs of researchers and began interacting more with other libraries, the value of standard cataloging  practices came to be recognized. With the advent of automated database technologies, catalogers began to establish 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 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. Standards for authority metadata: Standards for object identification, controlled by an identification-authority: Standards for identified-object metadata (examples): vCard, Dublin Core, etc.