The essence of XML

TLDR

The W3C promotes XML and related standards such as XML Schema, XQuery, and XPath, and XML Schema defines named and structural types based on tree grammars. The paper formalizes XML Schema, studying the relation between named and structural types and between matching and validation, building on prior work such as XDuce and Relax NG. The authors analyze the relationships between named types, structural types, matching, and validation within XML Schema, extending previous formalizations. The resulting formal semantics is incorporated into the official XQuery and XPath specifications, marking an early adoption of formal methods by a standards body.

Abstract

The World-Wide Web Consortium (W3C) promotes XML and related standards, including XML Schema, XQuery, and XPath. This paper describes a formalization of XML Schema. A formal semantics based on these ideas is part of the official XQuery and XPath specification, one of the first uses of formal methods by a standards body. XML Schema features both named and structural types, with structure based on tree grammars. While structural types and matching have been studied in other work (notably XDuce, Relax NG, and a previous formalization of XML Schema), this is the first work to study the relation between named types and structural types, and the relation between matching and validation.