Authority control is an important part of the cataloging process, for it brings consistency to the access points in library catalogs, which in turn enhances the discovery and retrieval of resources. It ensures that these access points are unique and consistent in content and form, and it provides a network of linkages for variant and related headings in the catalog. Reference to an authority file maintains consistency in controlled access points, while cross-references and the adjacent display of identical access points have been the primary methods used to accomplish the necessary linkages in the catalog. In Web-based catalogs, however, hypertext links are beginning to provide more direct catalog linkages, relieving the user of the need to retype a search query and perhaps introduce new errors in the process.
Discussions of authority control for music focus primarily on different aspects of bibliographic relationships, for it is the extensive existence of these relationships among music materials that creates the need for authority control. The literature of music librarianship on this topic is not extensive, but one study examined the types and extent of relationships in depth and discovered that relatedness is a pervasive characteristic of music materials.  Another study examined bibliographic families, i.e., that "set of works related to one another because they have common ideational and semantic content," revealing that the many instantiations of a musical work can make for a complex network of relationships. 
One particularly important authority control device for music is the uniform title. Barbara Tillett was among the first to discuss formally the uniform title in the context of bibliographic relationships, noting that it was used as a common device for linking related manifestations of a work and related works.  In an early empirical study, Richard Smiraglia examined a sample of musical works to determine the extent of need for uniform titles.  His research showed that virtually the entire sample yielded multiple manifestations and that the majority of these had titles proper differing from that of the first edition of the work. From these results Smiraglia concluded that uniform titles are a necessary part of the description of musical works and are needed to serve as authority control collocating devices. In another extensive article, this author traced the history and development of the uniform title, discussing the evolution from its early use for anonymous classics, sacred scriptures and specified publication forms, to its broader use today for any type of material in any format as the need warrants.  It is revealing that a large portion of the Anglo-American Cataloguing Rules for uniform titles is devoted to the application of uniform titles to musical works. 
Research has demonstrated that authority control is particularly essential for bibliographic records for music resources.  Many factors contribute to the extensive relatedness of music materials, including the high occurrence of works with generic form titles (e.g., Quartet or Symphony); the high occurrence of multiple editions and multiple recordings of the same work; the wide variety of presentation formats for the same work (e.g., full score, vocal score, etc.); and the high occurrence of arrangements, selections, and other bibliographic relationships for music materials. The international music publishing marketplace also contributes to the need for authority control. It is not uncommon for composer and performer names to appear in many different forms, languages, and scripts, or for works to be published under varying titles. Thus, authority control in terms of authorized forms of names and uniform titles has long been a standard part of life for the music cataloger. With the expanding environment of information organization, however, we need to take a new look at …