Hi, I wrote to the list a few months back asking about expressing FRBR relationships in MODS. Based on feedback from several people, we have developed a preliminary implementation of a hierarchical catalog for our collections, which you can try out here: http://test.perseus.tufts.edu/hopper/catalog One particularly nice example is this page: http://test.perseus.tufts.edu/hopper/catalog?field1=genre&term1=Science%20and% 20Mathematics The interface is designed to highlight the work/expression/manifestation levels. Works are defined in MADS records, expressions and manifestations in MODS records. The system runs in the eXist XML database. The catalog contains a combination of three collections: Perseus Greco-Roman materials, a new collection of Civil War-era texts, and several early modern scientific works, the online versions of which are actually hosted at the Linda Hall library at U Missouri, Kansas City. Neither the records nor the interface are entirely consistent yet, or entirely complient with standards. In particular, the ancient texts do not yet have classifications and subjects at the work level, and the American collection doesn't show up in the "genre" column. David Mimno Perseus Project, Tufts University