ABSTRACT
The entity-relationship model in the IFLA draft Functional Requirements of Bibliographic Records (FRBR) provides a useful mechanism for re-examining the multiple-versions problem in serials cataloging. The model provides a hierarchy of levels of abstraction that accommodates versions at both the concrete level of an exact reproduction of text, etc. (the manifestation level), and a more abstract level of an approximate reproduction of essential content (the expression level). Such a flexible model is especially useful given the expansion of novel version classes, especially that of dynamic remotely-accessible electronic documents. But along with the increase in usefulness afforded by the FRBR model comes an inevitable increase in ambiguity regarding what constitutes a version within the model, and at what level of that model, and ultimately what constitutes a work.
