A sufficient and necessary condition for the consistency of XML DTDs

Abstract

Recently, XML has emerged as a standard for representing and exchanging data on the World Wide Web. As a result, there is a trend of increasing amount of XML documents that publish information on the Web from various data sources. A Document Type Definition (DTD) describes the structure of a set of similar XML documents and serves as the schema for XML documents. The World Wide Web Consortium has defined the grammar for specifying DTDs; however, even a syntactically correct DTD might be inconsistent in the sense that there exist no XML documents conforming to the structure imposed by the DTD. In this paper, we formalize the notion of the consistency of DTDs, and identify a sufficient and necessary condition for a DTD to be consistent. © Springer-Verlag Berlin Heidelberg 2003.