Xalan-Java implements the W3C Recommendation 16 November 1999 XSL Transformations (XSLT) Version 1.0.

XLST is a stylesheet language for transforming XML documents into other XML documents, HTML documents, other document types, or text. The language includes the XSL Transformation vocabulary and XPath, a language for addressing parts of an XML document. An XSL stylesheet describes how to transform the tree of nodes in the XML input into another tree of nodes.