NEPOMUK Annotation Ontology Specification
The annotation ontology provides vocabulary that enables users to attach custom descriptions, identifiers, tags and ratings to resources on their desktop. Via other properties, the user is also able to make generic relationships between related resources explicit. Some relationships between resources are too general to be included at the domain ontology level. Instead, these properties are also defined in the annotation ontology. Given the high-level status of this ontology, these propreties can be used to link any related resources on the user's desktop, as well as provide custom human-readable textual annotations.