[RSS] [Google]


contact us

Library Philosophy and Practice Vol. 5, No. 2 (Spring 2003)

ISSN 1522-0222

Hierarchical Gaps and Subject Authority Control Processing : an Assessment

Daniel CannCasciato

Head of Cataloging


Catalog Librarian
Central Washington University Library
Ellensburg WA 98926-7548


Subject authority control procedures vary widely from library to library. Some processes are manual, they have varying staffing levels, and many are out-sourced and automated. There are two main goals behind the application of these procedures. The first is to standardize the terminology which is used in bibliographic records. This facilitates patron access to the collections and is significant to the fulfillment of the second of Cutter's objectives--to allow the patron to find what a library has by subject. The secondary effect of a subject authority control procedure is to help guide a patron from general, broad terminology to more specific, narrower headings which he or she might need. This need for records from the upper hierarchy is not unique to subject headings. Name headings for subordinate bodies exhibit the same requirement, although in what is generally a more contained environment. Name headings do not need to fit within any hierarchy other than their own, while subject headings are part of an overall schema. The name authority record (NAR) for a subordinate body, (e.g.,International Business Machines Corporation. Federal Systems Division), would require that the NAR for the parent body (International Business Machines Corporation) also be included in the catalog. For topical subject headings, however, this can become significantly more complex.

The complexity of hierarchical references can be demonstrated in a variety of ways. For example, to guide a patron to the speciesVenturia inaequalis (the fungal cause of Apple Scab) requires a long chain of linkages in terminology. A gap in that linkage compromises the effectiveness of the guidance we provide for our patrons. In Central Washington University Library's catalog the use of the term Venturia inaequalis on a bibliographic record required the addition of five subject authority records in addition to the one forVenturia inaequalis to provide a full hierarchical guide. The full hierarchical path beginning atFungi is shown in Figure 1. Items in bold are those for which the subject terminology is not on a bibliographic record. The authority records for those terms were added to the catalog to create a full reference structure for a patron to follow. Thus, a patron could enter a search at any point in the hierarchy and be led to the lone item we have that might be of interest.

Figure 1







                       Venturia inaequalis

A simpler example is that of the speciesChinese mitten crab (Eriocheir sinensis). Our catalog lacked the authority record for the immediately higher term, the genus,Eriocheir. Without the addition of that intervening terminology, a patron would not get from the family,Grapsidae, to the progressively narrower terms.

In this study we examined nine months of reports of new topical or geographic subject headings in our catalog. We downloaded new authority records when needed. We then examined those newly downloaded records to determine if they needed supporting authority records based on the broader terms from those new headings.

Literature Review

Very little is written on the actual subject control process. Most of the literature available discusses the fact that authority control is beneficial to patrons. "The true purpose of authority control should be to help the user move effortlessly from his/her terminology (natural language) to the terms in use (controlled vocabulary) of the system to locate all materials (objects) that are relevant ." (Micco, 1996: 1). A problem in academic libraries is subject authority control. Dalrymple and Younger (1991) report that there must be informed feedback for users when performing subject searches.

Some literature relates to specific online catalog systems. Krieger (1990) explains that searching by subject in the Dynix system is somewhat cumbersome because although the first search screen brings up a see or use for reference, related terms, broad terms, and narrower terms must be found by performing a related term command search. In a comparison between two systems, one with authority control and one without, the authors discovered that users performed subject searches more often than title searches (Wilkes, Nelson, 1995). The authors point out that controlled vocabulary is a problem because if users did not know the correct LCSH term, they would often not get results from their search in the system without authority control. The authors state that if users had consulted the print version of LCSH (kept near the terminals) they would have been able to determine broader terms, narrower terms, related terms, "use fors," etc. Since many users do not understand the idea of controlled vocabulary, it is more useful to have these references built in to the online catalog system. Chan and Vizine-Goetz (1998) discuss the feasibility of automatically generating a subject validation file from OCLC. They do not, however, discuss hierarchical issues.

Micco (1996) explains ". the user should be able to use a hierarchical classification to enter the system at the desired level of specificity in the topic of their choice with the option of broadening or narrowing a search that is not successful." (2). She continues by stating that currently (as of 1996) that option is not available and a hierarchical system needs to be implemented for that to occur.

Clack (1990) addresses very briefly the need for hierarchical records in the catalog even when the term has not been used as a subject heading on a bibliographic record. No further detail is given on this topic. Ludy (1985) also briefly describes the benefit of having the authority record for the broader term, even though that term does not appear in a bibliographic record. Michael Gorman (2002) refers to "proceeding from the general to the specific and following the syndetic structures of bibliographic control" as a characteristic of a good librarian (11).

The general concept of subject authority control, and authority control in general, is well covered. Its benefits are noted and recommended. Overall, though, in none of the literature we reviewed have we found a discussion of the frequency of the occurrence of hierarchical gaps in the authority control process - and thus in the catalog - nor of the possible impacts of those gaps.


For this study we have reviewed nine months of subject printouts from an Innovative Interfaces, Inc. integrated library system. We looked for new topical and geographic headings only. We omitted names and titles used as subjects. We also omitted most music headings (those covering arrangements, instrumentation, etc.) from this study, as their processing is handled by a separate workflow.

This review resulted in the identification of 331 new topical headings to Cattrax, the Central Washington University Library catalog. For those new headings, we downloaded the appropriate authority records from OCLC . We subsequently searched each of the broader terms for those topical headings in the catalog, identifying those new broader headings that were not represented by an authority record of their own. Those terms that required an authority record were then searched in OCLC and the records downloaded to the catalog. The process was repeated until there were no further authority records needing downloading into the catalog. We searched both explicit and implicit broader terms.

An explicit broader term is one identified on the subject authority record itself as MARC tag 550 (or 551) with a $w g. It is also known as a broader term, or BT. Implicit broader terms are those of the type for the headingPacific Gulf Yupik women. This topical heading requires the subject authority record forPacific Gulf Yupik Eskimos, because it is only on that authority that references from variant terminology reside. Without the authority record for this implicit broader term, references from the variantsAlutiiq Eskimos, South Alaska Eskimos, Sugpiak Eskimos, Suqpiaq Eskimos, etc., would not be available for our patrons. Similarly, for river valley headings and watersheds the river itself was searched.

Broader terms created for the specific purpose of filling a reference hierarchy, while searched in OCLC, were not downloaded to the local catalog if references were not needed. In general, these types of headings take the form [Topic] $x [Sub-topic] [Topic] $z[Geographic subdivision]. For example, the new heading ofAguarico River Valley (Ecuador) had the explicit broader term ofRivers $z Ecuador. The explicit broader term was searched in the utility, but as no broader terms existed on the authority record for that formulated heading, the authority record itself forRivers $z Ecuador was not downloaded into the local catalog. Depending on the limitations of the catalog software being used by a library, this practice would vary.


Many of the broader terms for the new headings were already in the database. Of the 331 new headings first downloaded, 42 subsequent new authority records (13.5%) were added. Of those 42, seven required new authority records. Of those seven, five new records were added. Of those five, two were added; and finally, of those two, one new authority record was added to the database. In all, 60 supplemental authority records were added to the database, which was an extra 17% beyond the original new headings list of 331. Without those gaps in the hierarchy being filled, it would have been impossible for a user to get fromLife scientists toWomen marine mammalogists, for example.

Contrary to expectations, the new headings were not overwhelmingly scientific in nature (seeAppendix). They did include scientific terms, but also included terminology related to agriculture, religion, technology, relationships, geographic locations, culture, and literature.


Based on this study, there are significant numbers of new subjects whose authority records need additional authority records downloaded to fill in the reference hierarchy. There was no predictive subject area in which needed broader term headings are easily identified. Some local library systems' report capabilities might be able to identify subject headings with broader terms not represented in the catalog by bibliographic records. Many will not be able to do so. The Central Washington University Library catalog system would not create a report of headings for which the broader term is not also used on a bibliographic record or not supported by an authority record above it in the hierarchy. It will report if the heading (MARC 1XX field) from an authority record is not found also on a bibliographic record.

Subject authority control procedures have been sporadic at Central Washington University Library. Currency in maintenance of this process could have an impact on the percentage of items needing the additional broader term authority records.

This study has shown, at least preliminarily, that in subject authority control procedures there is a need to search not only the subject authority record for the new heading itself, but also for those headings that support hierarchical searching and the syndetic structure.

Although it may seem time consuming to check the new heading for hierarchical gaps, doing so will provide the links a user needs to find material on a subject he or she is researching. It may save time in the long run, by providing online guidance to users who do not understand and will not learn about hierarchical relationships in subjects.

One of the primary goals of the catalog is to facilitate the use of the collection by the patron. A fully employed hierarchy must be available to the patron, to assist in the retrieval of pertinent materials.


Chan, Lois Mai and Vizine-Goetz, Diane. (1998) "Toward a Computer-generated Subject Validation File: Feasibility and Usefulness." Library Resources & Technical Services (42:1: January 1998): 45-60.

Clack, Doris Hargrett. (1990).Authority Control: Principles, Applications, and Instructions. Chicago: American Library Association. 174.

Dalrymple, Prudence W. and Younger, Jennifer A. (1991) "From Authority Control to Informed Retrieval: Framing the Expanded Domain of Subject Access."College & Research Libraries (52:2: March 1991):139-149.

Gorman, Michael. (2002) "Why Teach Cataloging and Classification?" Cataloging and Classification Quarterly (34:1&2):1-13.

Krieger, Michael T. (1990) "Subject Authority Control on the Dynix System."Cataloging & Classification Quarterly (12:1):103-115.

Ludy, Lorene E. (1985) "OSU Libraries' Use of Library of Congress Subject Authority File."Information Technology and Libraries(4:1): March 1985:155-160.

Micco, Mary. (1996) "Subject Authority Control in the World of Internet."LIBRES: Library and Information Science Research, (6:3)September 1996: 7 pages.

Wilkes, Adeline and Nelson, Antoinette.(1995) "Subject Searching in Two Online Catalogs: Authority Control vs. Non-authority Control."Cataloging & Classification Quarterly(20:4)57-79.


contact us