Type-consistent Digital Objects
The fundamental element upon which modern Digital Libraries (DLs) are built is that of the digital object [19]. Digital objects can be conceived as compound artifacts that wrap digital material in terms of four elements: its content, its metadata, its relationships with other objects and its behavior. It is often the case that material in DLs can be classified in categories whose members present similar, if not identical, characteristics and behavior. Should we consider a DL comprised of “papers” and “photographs”, two respective groups of digital objects could be created to cater for the two readily discernable categories of digital material.