Abstract
Metadata represent the vehicle by which digital documents can be efficiently indexed and retrieved. The need for such kind of information is particularly evident in multimedia digital libraries, which store documents dealing with different types of media (text, images, sound, video). In this context, a relevant metadata function consists in superimposing some sort of conceptual organization over the unstructured information space proper to these digital repositories, in order to facilitate the intelligent retrieval of the original documents. To this purpose, the usage of conceptual annotations seems quite promising. In this paper, we propose a two-steps annotation approach by which conceptual annotations, represented in NKRL (Narrative Knowledge Representation Language) [7,8], are associated with multimedia documents and used during retrieval operations. We then present how documents and metadata can be stored and managed on persistent storage.