What is XQuery

Digital libraries are systems that contain organized collections of objects, serving in their most basic functions as a mirror of the traditional library that contains paper documents. Most of the information contained in the collections of a digital library consists of documents, which can evolve with time. That is, a document can be modified to obtain a new document, and digital library users may want access to any of those versions. This introduces in digital libraries the problem of versioning, a problem that is also of interest for the hypertext community and the Semantic Web community. Some domains in which document evolution is a very important issue are the legislative domain (Arnold-Moore, 1997; Martínez González, de la Fuente, Derniame & Pedrero, 2003a; Vitali, 1999), the management of errata made to scientific articles (Poworotznek, 2003), software construction (Conradi & Westfechtel, 1998), and collaborative e-learning (Brooks, Cooke & Vassileva, 2003).