Annotation of multimedia resources supports a wide range of applications, ranging from associating metadata with multimedia resources or parts of these resources, to the collaborative use of multimedia resources through the act of distributed authoring and annotation of resources. Most annotation frameworks, however, are based on a closed approach, where the annotations data is limited to the annotation framework, and cannot readily be reused in other application scenarios. We present a declarative approach to multimedia annotations, which represents the annotations in an XML format independent from the multimedia resources. Using this declarative approach, multimedia annotations can be used in an easier and more flexible way, enabling application scenarios such as third-party annotations and annotation aggregation and filtering.

Events and periods are not objectively existing phenomena, but concepts we use to organize our knowledge of history. They make historical change comprehensible and help us orient ourselves with respect to the history of the culture in which we participate. Thus they are indispensable for describing both the content of history scholarship and the context of documents that serve as evidence for that scholarship. As historical discourse shifts its emphases and new aspects of the past come to be considered significant, periods and events are subject to constant change. Despite this change, we can model periods and events in systems of knowledge organization because it is possible to discern and formally describe relatively stable recurrent patterns in their narration.

People conventionally refer to an action or occurrence taking place at a certain time at a specific location as an event. This notion is potentially useful for connecting individual facts recorded in the rapidly growing collection of linked data sets and for discovering more complex relationships between data. In this paper, we provide an overview and comparison of existing RDFS+OWL event models, looking at the different choices they make of how to represent events. We describe a recommended model for publishing records of events as Linked Data. We present tools for populating this model and a prototype of an "event directory" web service, which can be used to locate stable URIs for events that have occurred and to provide RDFS+OWL descriptions of them and links to related resources.