Authority Control

MeSH, LC Children's, Sears & Genre/Form Headings

LTI's approach to NLM MeSH, LC Children's, Genre/Form headings and Sears authority control parallels procedures for LCSH headings. Separate files of authorized headings are maintained for each controlled vocabulary.

NLM MeSH Headings

Using the National Library of Medicine's MeSH authorities file, LTI offers a MeSH authority control service to medical and health sciences libraries. NLM headings are updated annually. Topical (650) and a few geographical (651) subject headings having a second indicator of '2' are eligible for MeSH processing. Major and minor descriptors, as well as subheadings, are included in the MeSH file. Conversion of MeSH to LCSH is not an option.

LC Children's Subject Headings

In 1996 LC started distribution of Children's authority records based on Library of Congress usage. Because LC Children's headings can contain adult headings considered appropriate for children's use, LC Children's headings are first matched against LC's file of Children's authority records, and then against standard LC subject and name authority files.

Given that conflicts do occur between LCSH and LC Children's headings (e.g., LCSH Swine versus the LC Children's Pigs), libraries may want to consult with their ILS vendor about the desirability of integrating the two controlled vocabularies in a single index.

LTI offers four options for processing LC Children's headings: 1) authorize them as LC Children's headings using LC's (sj control number) Children's authority records; 2) convert them to LCSH; 3) delete them from the library's bibliographic records, or, 4) to ignore them completely during processing. These same processing options are available for Sears.

When Children's headings are to be converted to LCSH, during a pre-processing routine, second indicator codes of '1' in 6XX fields are changed globally to '0' and the subject subdivisions Juvenile literature, Juvenile fiction, etc. are added to the converted heading. Following authority control, resulting duplicate headings are removed from records. For example, assume the library's source catalog record has the following two subject headings:

Following authority control two identical LCSH headings will exist--i.e., $aFishes$vJuvenile literature. One of these headings will be deleted because a final LTI check eliminates controlled headings that are truly identical after authority control.

Children's headings having no LCSH equivalent--e.g., French language materials--are retained, though the second indicator is still set to 0.

Sears Subject Headings

Authority control can also be exerted over Sears subject headings (i.e., 6XX fields having a second indicator of '7' [MARC 21] or '8' [OCLC]). Sears headings are distributed by H.W. Wilson and are updated as new editions appear. For libraries that subscribe to Sears subject headings authority control: Note that the 19th edition (2007) of the Sears authority records allows the use of "Juvenile" subdivisions--e.g., "$xJuvenile literature," "$xJuvenile fiction," etc. These subdivisions are now validated as legitimate floats in Sears headings instead of being altered or deleted.

Genre/Form Heading Processing

Genre headings in 655 fields are authorized using LTI's Genre Heading processing option. At this time the service is limited to Library of Congress and NLM MeSH subject headings, as well as those found in the publication, Guidelines on Subject Access to Individual Works of Fiction, Drama, Etc. Headings which include $2lcsh, $2mesh, or $2gsafd are pulled from bibliographic records for processing and compared against LTI-created authority records derived from official and semi-official sources. Content of the headings is updated to current usage, including correction of typographical errors in entry. If the subfield coding is absent, headings will still be pulled if the code is present following a space, e.g. $aFiction lcsh will be pulled and $2 inserted to create $aFiction$2lcsh. Typos in the codes are also corrected: $2lsch is corrected to $2lcsh.

The complete file of GSAFD authority records is available for free download on the Internet. LTI may authorize additional genre/form controlled vocabularies in the future when demand and authority record availability warrant it.

If genre headings are authorized, they are returned in either the old or new style tagging. The old style uses a second indicator of 7, with a $2 subfield identifying the controlled vocabulary. GSAFD headings are always coded in this fashion. The new style alternative returns genre headings in 655 fields with the second indicator identifying whether the heading is LCSH or MeSH.

Libraries have the option of converting GSAFD headings to LCSH. They also have the option of converting genre/form headings that may have been coded as topical subjects (650) to 655. The latter conversion occurs only with stand-alone $a genre/form headings. If a LCSH topical heading includes another subfield-such as $v, $x, $y, or $z--the heading is not considered a form heading. Thus far relatively few LC genre/form authority records [tagged 155] have been distributed and these are limited to motion pictures, television programs and videos. When returned to libraries these authority records are placed in a separate file; they are not included with subject-related authority records.

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