Annotations: Enriching a Digital Library

This paper presents the results of a study on the semantics of the concept of annotation. It specifically deals with annotations in the context of digital libraries. In the light of those considerations, general characteristics and features of an annotation service are introduced. The OpenDLib digital library is adopted as a framework of reference for our ongoing research, so the paper presents the annotations extension to the OpenDLib digital library, where the extension regards both the adopted document model and the architecture. The final part of the paper discusses and evaluates if OpenDLib has the expressive power of representing the presented semantics of annotations.