Authority control is essential for effective local system searching. It improves access dramatically by providing consistency in the form of headings used to identify authors, place names, preferred titles, series, and subjects. Keywords offer extensive and powerful search capabilities, but they are no substitute for authority control.
Authority control generally takes place following all other database work, e.g., duplicate record resolution, merging bibliographic records of multiple libraries into a single database, etc. Libraries migrating from one local system to another often take this opportunity to re-authorize their bibliographic records and obtain a clean file of up-to-date authority records prior to implementing the new system.
From a processing perspective, batch authority control is achieved through a series of clean-up operations.
Ideally, all headings in the library's database should match an LC/PCC authority record, but in practice some headings do not link. After all possible headings are matched to an authority record, they are inserted back into the bibliographic records