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W3C

XSL Transformations (XSLT) Version 4.0

W3C Editor's Draft 23 February 2026

This version:
https://qt4cg.org/specifications/xslt-40/
Latest version:
https://qt4cg.org/specifications/xslt-40/
Most recent Recommendation of XSL Transformations (XSLT):
https://www.w3.org/TR/xslt-30/
Editor:
Michael Kay, Saxonica <http://www.saxonica.com/>

The following associated resources are available: Specification in XML format, XSD 1.1 Schema for XSLT 4.0 Stylesheets (non-normative), Relax-NG Schema for XSLT 4.0 Stylesheets (non-normative), Stylesheet for XML-to-JSON conversion (non-normative)


Abstract

This specification defines the syntax and semantics of XSLT 4.0, a language designed primarily for transforming XML documents into other XML documents, but also offering support for other data formats including JSON, HTML, and CSV.

XSLT 4.0 is a revised version of the XSLT 3.0 Recommendation [XSLT 3.0] published on 8 June 2017. Changes are presented in 1.2 What’s New in XSLT 4.0?.

XSLT 4.0 is designed to be used in conjunction with XPath 4.0, which is defined in [XPath 4.0]. XSLT shares the same data model as XPath 4.0, which is defined in [XDM 4.0], and it uses the library of functions and operators defined in [Functions and Operators 4.0]. XPath 4.0 and the underlying function library introduce a number of enhancements, for example the availability of union and record types.

This document contains hyperlinks to specific sections or definitions within other documents in this family of specifications. These links are indicated visually by a superscript identifying the target specification: for example XP for XPath 4.0, DM for the XDM data model version 4.0, FO for Functions and Operators version 4.0.

Status of this Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

This document has no official standing. It is produced by the editor as a proposal for community review. Insofar as it copies large amounts of text from the W3C XSLT 3.0 Recommendation, W3C copyright and similar provisions apply.

This document is a working draft developed and maintained by a W3C Community Group, the XQuery and XSLT Extensions Community Group unofficially known as QT4CG (where "QT" denotes Query and Transformation). This draft is work in progress and should not be considered either stable or complete. Standard W3C copyright and patent conditions apply.

The community group welcomes comments on the specification. Comments are best submitted as issues on the group's GitHub repository.

The community group maintains two extensive test suites, one oriented to XQuery and XPath, the other to XSLT. These can be found at qt4tests and xslt40-test respectively. New tests, or suggestions for correcting existing tests, are welcome. The test suites include extensive metadata describing the conditions for applicability of each test case as well as the expected results. They do not include any test drivers for executing the tests: each implementation is expected to provide its own test driver.

Dedication

The publications of this community group are dedicated to our co-chair, Michael Sperberg-McQueen (1954–2024).