Digital library resources as a basis for collaborative work

The creation of large, networked, digital document resources has greatly facilitated information access and dissemination. We suggest that such resources can further enhance how we work with information, namely, that they can provide a substrate that supports collaborative work. We focus on one form of collaboration, annotation, by which we mean any of an open-ended number of creative document manipulations which are useful to record and to share with others. Widespread digital document dissemination required technological enablers, such as web clients and servers. The resulting infrastructure is one in which information may be widely shared by individuals across administrative boundaries. To achieve the same ubiquitous availability for annotation requires providing support for spontaneous collaboration, that is, for collaboration across administrative boundaries without significant prior agreements. Annotation is not more commonplace, we suggest, because the technological needs of spontaneous collaboration are challenging. We have developed a document model, called multivalent documents, which provides a means to address these challenges. In the multivalent document model, a document comprises distributed data and program resources, called layers and behaviors, respectively. Since most document functionality is implemented by behaviors, the model is highly extensible, and can accommodate