Documentation changes

The documentation has been updated to integrate information about features of the 4.0 specifications implemented in this release. Information in the reference sections XSLT elements, XPath syntax and Function library has been updated to align with the draft 4.0 specifications (dated 28 January 2026). In particular, note that the signatures for functions in the Function library have been updated to align with the 4.0 specification, and use the same updated notation (e.g. giving default values for parameters that can be omitted), and these may have changed since XPath 3.1. The XPath syntax section has been reorganised and expanded.

Information about new 4.0 features is highlighted in the Saxon documentation with a yellow colored side-bar and the QT4 lightbulb image. The main objective of the Saxon documentation is to inform users about the implementation status for 4.0 features, rather than being an actual guide to the new 4.0 features. Users are recommended to see the specifications for full details and examples.

References in this document such as "PR 1497" refer to GitHub pull requests for the repository in which the draft 4.0 language specifications are maintained. This particular pull request can be found in GitHub at https://github.com/qt4cg/qtspecs/pull/1497. Since early 2026, change-marked versions of the specification illustrating the effect of each PR are also available, at https://qt4cg.org/available-prs.html.