XSV - The XML Schema Validator Tutorial

XSV (XML Schema Validator) is an open source schema-aware processor which implements standards defined in the XML Schema specification. XSV was developed at the Language Technology Group of the Human Communication Research Centre in the Division of Informatics at the University of Edinburgh, with support the World Wide Web Consortium (W3C). It is widely accepted in the XML Schema development community as being the official reference implementation for the XML Schema language. Stylus Studio is the only XML IDE to provide seamless XML validation support for XSV. This tutorial covers how to parse and validate XML instance documents, as well as how to check your schemas to make sure they comply with the XML Schema Specification.

http://www.stylusstudio.com/xml_schema/xsv.html