The Library of Congress maintains two separate authority files: one for names and one for subjects.
LC staff and NACO participants create headings for personal, corporate, conference and geographic names, as well as uniform title and
series headings.
LC creates records for headings and heading subdivision combinations included in Library of Congress Subject Headings (LCSH). LC does not necessarily create a record for every unique heading subdivision combination assigned to a bibliographic record.
Because LCSH excludes the following categories of headings, LC creates no subject authority records for:
LC creates and distributes name authority records for the first two categories.
The subject authority file does not contain records for non-LC authority systems such as MeSH (Medical Subject Headings), NAL (National Agricultural Library), and LAC (Library and Archives Canada).
LC assigns authority record control numbers (LCCNs) to all authority records. The control number consists of an alphabetic prefix
plus eight or ten digits. The alphabetic prefix indicates which system created the authority record.
System | Assigned prefix(es) |
---|---|
British Library | nb - for name headings |
LC |
dg - for demographic terms (LCDGT) gf - for genre/form terms (LCGFT) mp - for medium of performance terms (LCMPT) n - for name headings sh - for subject headings (LCSH) sj - for subject headings for children (CSH) |
OCLC | no - for name headings |
RLIN |
nr - for name headings Note: No new authority records were added via RLIN after 2007. |
SkyRiver | ns - for name headings |
Note: In-process records for proposed LC subject headings are found only in the Library of Congress online system. These records have LCCNs prefixed with sp.
LC subject records may contain the following unique characteristics:
The LC subject authority file contains only headings and cross-references from the current edition of LCSH, its supplements, and weekly lists. Cross-references that link subject headings formerly used to their current forms may or may not be present.
Topical subject headings (field 150) and topical subdivision headings (field 180) do not always support subdivision by place.
To indicate that field 150 and/or field 180 may be subdivided geographically, the fixed-field element Geo subd contains code i.
Code n or a fill character, █ in Geo subd indicates that the heading in field 150 and/ or field 180 may not be subdivided geographically.