I is World War, 1914-1918 . Typing World War I or World War One or First World War into a subject search in a library catalog would return no records. It is crucial to know a subject heading before conducting a subject search One good way of learning a subject heading is to do a successful keyword search and then examine the subject headings of the relevant items you find. The words following the dashes are subheadings. Periodical indexes use other types of subject headings, often called descriptors .
Descriptors are generally words or phrases that describe a topic.
Like Library of Congress Subject Headings they use a predefined vocabulary. Unlike Library of Congress Subject Headings, they do not have subheadings. Copyright 1999-2001, University of Denver .