A very important task for cataloguers, which determines the efficiency in catalogue searches, is the “authority control” . Authority control is the process through which terms (“headings” in cataloguing terminology) that may be used as access points to a bibliographic record are “authorized” or “established” in a particular form.
Almost all data in the fields of a bibliographic record may act as access points to the source but not all of them can be “controlled” in authority records. For example the title of a book as found on a title page , the place or the year of publication, codes or keywords , cannot be controlled. More specifically authority control is only applied to personal or corporate names, uniform titles (title used to represent a work when this has appeared under varying titles) and topical subjects, meaning any term that can be the subject of a library document, such as a concept, a place, an event etc.
Authority control resolves the problems of name and definition ambiguities and facilitates the process of identification which is essential when constructing an access point . In library cataloguing, for every term which is going to be used as an access point to a bibliographic record, an authority record is created. The authority record is like an identification statement for this term/heading and keeps control on its use by defining a unique form of heading and the context for its usage, as well as it relates the heading with variant forms or other related headings.
This way authority control improves the ability for both librarians and library users to access material in the catalogues and helps to maintain consistency in the usage of headings that is reflected in the whole catalogue.
The first component of an authority record is the authorized heading. This is the name of an entity that is established in one particular form by a bibliographic agency according to cataloguing rules. The preferred (authorized /established) form of name is unique and it is used consistently throughout the catalogue, whenever this term is needed as an access point in a bibliographic record. For example the Library of Congress assigned the appellation “Plato” as the established form of name for the Greek philosopher and the name form "Náfpaktos (Greece)" for the place known as “Lepanto” where the famous battle took place in 1571.
However there are variant names that can be used to describe a thing and these names can even take various forms. These various ways that can be used to refer to something must be also recorded in the authority record given that they can eventually be used as access points by users who are not supposed to be aware of authorized headings. Thus, creating cross references to the variant forms permits redirection to the authorized form of a name for an entity.
Authority records may additionally provide see-also references, i.e references that connect related headings and facilitate users search for related content. For example, if we are searching for material about "teaching" we are also suggested to search related documents under "education". Additional information about the authorized headings such as notes that indicate the context of name use is usually provided. These notes are particularly important for topical subjects because they define the exact scope and help cataloguers to select between various related concepts the appropriate subject heading. The notion of identity depends on how we define a category. Scope notes resolve the problem of definition ambiguity and help us understand the identity of the entities described.
In continuation an authority record may provide additional characteristics (attributes) of the entity identified. For example, the authority record for a personal name heading would provide information such as the place and date of birth and death, the profession etc. Respectively a record for a corporate name heading would provide information about the beginning date of an institution, the field of activity, the location etc.
The last component of an authority record is notes. Most often notes concern the citations for a consulted source where relevant information was found. For example the Library of Congress authority record for the poet Arthur Rimbaud, among others, includes a cross reference to the variant name "Alcide Bava" which the poet had used to sign one of his poems. The source where this pseudonym was found is included in the record.
To sum up, an authority record is created in order to control a heading. It is important for the cataloguer to use a heading as a single, distinct name for what is “described” in order to maintain consistency of usage of names and collocate the bibliographic records under the same group of resources depending on the search criterion. Bibliographic agencies apply specific cataloguing rules that specify the steps that have to be followed when authorizing an access point and how to ensure its uniqueness. The steps include the choice of the preferred form of the name, the choice of identifiers, their form, punctuation and order. Authority control is the key to efficiently organize a library catalogue. The main purpose is to maintain a consistent and well-organized catalogue that will benefit both users by easily accessing relevant content and cataloguers by facilitating them keeping up with their cataloguing tasks. To guarantee efficient user searches authority control must be an ongoing effort.