ABSTRACT
Nowadays, increasingly, documents are marked-up using eXtensible Mark-up Language (XML), the format standard for structured documents. In contrast to HTML, which is mainly layout-oriented, XML follows the fundamental concept of separating the logical structure of a document from its layout. This document logical structure can be exploited to allow a focused access to documents, where the aim is to return the most relevant fragments within documents as answers to queries, instead of whole documents. This entry describes approaches developed to query, represent, and rank XML fragments.
