When you are looking at a record for a book or other item in OneSearch, there are a few possibilities as to where the subject headings come from.

Catalog records

Some of what is in OneSearch is based on records in our back-end catalog. This includes physical books in our collection, ebooks, and certain other materials. You'll know you're looking at one of these because you'll see something like docid=alma991002191581105325 in the URL, and you'll see an MMS ID line on the page.

In these cases, English-language subject headings come mostly from the Library of Congress (LC) vocabulary. This is a system of topics, geographic places, names, titles, and various subdivisions. We also display subject headings from the Homosaurus vocabulary, which seeks to improve access to LGBTQ-related topics.

You might also see Spanish-language subject headings under Materia. These headings come from either Biblioteca Nacional de España (BNE) or Bilindex.

Records come from various sources, and the source of the record generally correlates with the quality of the subject headings. Print books that we acquire and put on our library shelves are mostly represented by records that come from WorldCat, a cooperative cataloging project. The average quality of the subject headings from WorldCat is high—most WorldCat records have accurate, up-to-date headings. Catalogers sometimes improve WorldCat records; when this happens, the changes are reflected in OneSearch within a day or two of the change.

Records representing electronic resources, such as ebooks and streaming video, are less reliable. Some of these are from WorldCat, but others are provided by vendors, and the subject headings are of lower quality. They might be inaccurate or missing entirely.

Central Index records

OneSearch contains millions of records, often of articles from journals, magazines, and newspapers, but also images, videos and other assorted materials, which are maintained in a central index by our vendor, Ex Libris. These records have subject headings that in many cases are based on Library of Congress, Medical Subject Headings (MeSH), or other vocabularies.

Filters

The filters on the left-hand side of results pages contain subjects associated with the records in the result set. These are not limited to LC or any of the other vocabularies mentioned above. It's a bit chaotic!

Problems with subject headings

The purpose of subject headings is to group similar titles together and help you discover worthwhile resources. But it is an imperfect process. Subjects for a particular title might be inaccurate, a vendor might have coded a non-LC heading as LC, or you might even come across headings that seem objectionable.

Because of the huge number of records shown in OneSearch, the ARC Library cannot commit to properly maintaining subject headings in all titles. However, if you come across a subject that strikes you as offensive, objectionable or otherwise problematic, we invite you to contact the library via our Ask Us page. We'll take a look and see if we can improve the record ourselves or report the problem as something to be fixed by others.