The description of collections is becoming increasingly important in the context of networked information services and is an important underpinning for developing a collective resource. This view has emerged clearly through the MODELS project [1], where it has influenced the course of the clumps and hybrid libraries [2] who are working with collection and service descriptions, and in UKOLN's recent work on retrospective conversion [3]. In the latter case, a strong view is emerging that libraries need to complement itembased description with description at a higher level. A particular feature of this discussion is that this would complement current work in the archives community and that descriptions at this shared level of granularity would facilitate crossdomain working (while acknowledging that collections may mean different things in the different library, archival and other content models). This has been corroborated by recent work which looks at research issues shared by libraries, archives and museums, where it was recognized that description at this level would support higher level navigation of the cultural resource and selection of particular resources for further searching [4].

The creation of collection descriptions allows the owners or curators of collections to disclose information about their existence and availability to interested parties. Although collection descriptions may take the form of unstructured textual documents, for example a set of Web pages describing a collection, there are significant advantages in describing collections using structured, open, standardized, machinereadable formats. Such descriptions enable: