For libraries lacking the staff or resources to maintain headings following batch authority control, exporting and re-authorizing the entire database every few years may be the only way to keep controlled headings in synch with LC.
When a database that has previously been authorized is re-submitted for authority control, there is no need to export item record data or the library's existing authority records. All the authority control vendor requires is the bibliographic records. After the re-authorization the library should be prepared to delete all its existing nationally distributed and local authority records. LC, LC Children's, LC Genre/Form, and NLM MeSH authority records are completely replaced as part of the re-authorization. Similarly, ILS software generates new provisional authority records for headings for which no nationally distributed authority record is available.
Following re-authorization, the library's catalog records are re-loaded into the local system database by "overlaying" on the ILS's record ID control number. New authority records and bibliographic records are loaded and new indexes are built.
Some libraries may not want to delete their old authority records either because they have added cross-references or notes or removed cross-references that they consider not useful for their catalog, or because they are advised by their ILS vendor to "overlay" the new authority records. At least one local system vendor encourages the retention of existing authority records by imposing a high fee to delete the library's old LC and/or local authority records. Retaining old authority records rather than starting fresh with authority records directly referenced in those bibliographic records, will result in several kinds of conflicts as described below. The list is not intended to be exhaustive. Such conflicts may be minor or major, frequent or infrequent-but they are inevitable and the library pays a price for keeping outdated and local authority records.
One of the benefits of a newly authorized database of bibliographic records is the corresponding files of comprehensive and up-to-date LC authority records. Why compromise that by mixing old authority records with new ones?