How to cite this paper

Kay, Michael. “The XSLT/XPath/XQuery 4.0 Standards: a High-Level Perspective.” Presented at Balisage: The Markup Conference 2026, Washington, DC, August 3 - 7, 2026. In Proceedings of Balisage: The Markup Conference 2026. Balisage Series on Markup Technologies, vol. 31 (2026). https://doi.org/10.4242/BalisageVol31.Kay01.

Balisage: The Markup Conference 2026
August 3 - 7, 2026

Balisage Paper: The XSLT/XPath/XQuery 4.0 Standards: a High-Level Perspective

Michael Kay

Founder and Director of Innovation

Saxonica

Michael Kay is the founder and Director of Innovation at Saxonica. He was the original developer of the Saxon XSLT and XQuery processor, and was the editor of the XSLT 2.0 and 3.0 specifications. He was instrumental in establishing a W3C community group to create 4.0 versions of the XSLT, XQuery, and XPath languages. Since 2004 Saxonica has been a leading participant in both the development of the language specifications and in delivering high quality implementations of the standards. Michael is based in Reading, UK.

Abstract

A W3C Community Group is in the process of developing proposals for 4.0 versions of XSLT, XPath, and XQuery (collectively, QT4). This paper describes the original objectives of this project and the extent to which they have been achieved. It does this within the framework of some general observations about standards and the factors that make standards successful and unsuccessful.

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Michael Kay. "A Proposal for XSLT 4.0". XML Prague, 2020. http://archive.xmlprague.cz/2020/files/xmlprague-2020-proceedings.pdf.

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Michael Kay. "Schema-Aware Conversion of XML to JSON". Presented at Balisage: The Markup Conference 2022, Washington, DC, July 31 - August 4, 2023. In Proceedings of Balisage: The Markup Conference 2023. Balisage Series on Markup Technologies, vol. 28 (2023). doi:https://doi.org/10.4242/BalisageVol28.Kay01.

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Michael Kay. Kay, Michael. "JNodes: a New Model for Navigating JSON Trees". Presented at Balisage: The Markup Conference 2025, Washington, DC, August 4 - 8, 2025. In Proceedings of Balisage: The Markup Conference 2025. Balisage Series on Markup Technologies, vol. 30 (2025). doi:https://doi.org/10.4242/BalisageVol30.Kay01.