Users expect search to be able to locate works about a concept/subject
Users expect search to also deliver works that are conceptually similar or items related to the search term; for example, in the case of beer, also beer bottles, labels, breweries
Users expect a search for a subject to be the first results
These types of keyword searches may coincide with controlled vocabularies (LCSH, MeSH, LC Genres, other thesauri that users know)