If information cannot be found when it is wanted, it cannot be integrated into the world of human knowledge or into an individual's personal knowledge base. Whether people want to write a newspaper article, complete a project, or learn about a new hobby, they need to be able to find information that relates to what they are doing and to what they want to know. The overall purpose of cataloging and knowledge organization is to help people achieve the goal of finding information as easily as possible when they need it. This goal may seem to be a simple one, but accomplishing it is not necessarily easy or straightforward. For example, the way in which information is described and organized should ideally be consistent within one information medium, compatible with other information media, and predictable and appropriate for different kinds of information...