Managing a digital library of legislation

We provide an overview of the Themis system, a commercial implementation of a digital library of legislation. Themis uses SGML to store legislation. This allows a single source document to be exported in a number of different formats and presentations. Themis also allows access to different versions of legislation by specifying a point-in-time at which the law is required. We discuss how this is achieved in Themis and how versioning impacts the storage of fragments of documents and management of references within and between documents.