A work is a deliberately created informing entity intended for communication. A work consists of abstract intellectual content that is distinct from any object that is its carrier. In library and information science, the importance of the work lies squarely with the problem of information retrieval. Works are mentefacts-intellectual (or mental) constructs that serve as artifacts of the cultures in which they arise. The meaning of a work is abstract at every level, from its creator’s conception of it, to its reception and inherence by its consumers. Works are a kind of informing object and are subject to the phenomenon of instantiation, or realization over time. Research has indicated a base typology of instantiation. The problem for information retrieval is to simultaneously collocate and disambiguate large sets of instantiations. Cataloging and bibliographc tradition stipulate an alphabetico-classed arrangement of works based on an authorship principle. FRBR provided an entity-relatio