A Common Annotation Framework

Annotating resources on the World Wide Web in a flexible manner is a key problem, yet there is no standard for annotations on the Web. We propose a design for CAF, a Common Annotation Framework that supports annotation across applications in a standard way. The framework is based on a principled logical model, and is designed to meet a wide set of annotation needs without overburdening any particular application with excessive functionality. It is flexible and extensible, and can support annotation of any media type with any media type. We discuss the structure and function of the CAF logical model, and we describe a proposed CAF schema. We explain how CAF can be extended and give examples. And we present a web-based annotation application built using CAF.