- The LC Authority File is comprised of two files: the LC Name Authority File (or the LC NACO file), and the LC Subject Authority File (or the LC SACO file). An important difference between Name Authorities (NACO) and Subject Authorities (SACO) is: NACO is done in real time, but SACO has to go through LC's Subject Approval process, which takes 3-4 months.
- The Division of the World, or: Is it a Name or a Subject?: to determine if an existing authority heading is a name or a subject, simply look at the authority record's Library of Congress Control Number (LCCN) in the 010 field. If the number begins with an "n," the heading is a name and resides in the Names, or NACO, file. If the number begins with an "s" (usually, if not always an "sh"), the heading is a subject and resides in the Subject, or SACO, file.
- To determine if a heading that a cataloger wishes to establish or propose is a name or subject, consult SHM H 405 and its summary.
- Important note: The MARC 21 tag of the authority record heading is not always indicative of whether the entity is a name or subject. Both names and subjects may be tagged 110 and 151. Only subjects are tagged 150. Only names are tagged 111 and 130 (titles are in the Names file), except possibly in older records.
- Geographic entities--Names vs. Subjects: Read SHM H 690, Background. Geographic entities of a jurisdictional nature, such as countries, states, provinces, counties, cities, and towns, are names. So are water, conservation, or ranger districts. These are human created corporate bodies, frequently governmental in nature, having jurisdiction over a specific geographical area. Natural features, on the other hand, such as mountains, mountain ranges, basins, plateaus, mesas, canyons, lakes, rivers, bays, capes, seas, and underwater features, are subjects.
- In addition, names also include any populated place, designated as "ppl" in GNIS or GEOnet. City sections are also considered to be Names. Subjects, on the other hand, also include geographic regions (Africa, East; Great Basin), and collective names for groups of jurisdictions (Hamptons (N.Y.)).
GPO catalogers consult the sources listed below for instructions on the name vs. subject authority files:
- SHM H 405 Name vs. Subject Authority File
- SHM H 690 Formulating Geographic Headings
- DCM Z1 (Descriptive Cataloging Manual, Z1): Appendix 1: Ambiguous Entities
- Library of Congress Rule Interpretations (LCRI): 23.1
- LCRI 24.1A: Ambiguous Entities
- MARC 21 Format for Bibliographic Data: Appendix E
- NACO Training for OCLC Libraries, rev. May 2001. Program for Cooperative Cataloging, Library of Congress. "Geographic Names: Things to remember."