Callisto: A Configurable Annotation Workbench.

In order to support a range of textual annotation tasks, we have developed a new annotation tool called Callisto. To promote task- specific specialization of the interface and associated constraint checking, Callisto provides a facility for the independent development, compilation and installation of task module plug-ins (in the form of Java Archive jar files). The common Callisto backend provides a set of annotation services to which all separate GUI components can subscribe, enabling a common framework through which annotation updates are propagated to all components. A number of annotation task models have already been defined, and those that are of very general applicability have been made easily re -configurable for small changes in task definition. Callisto is implemented in Java to make use of Java s considerable support for Unicode-encoded multilingual data. Callisto is freely available for downloading and use.