XQuery 3.1 implementation

Support for document projection is dropped. (Document projection allowed the document building process to filter a document as it was being constructed, to retain only those nodes needed for evaluation of a particular query. In most cases streamed execution of queries provides a more flexible and performant solution for this requirement.)

The rules for grouping in XQuery 3.1 (and related operations such as the distinct-values function) had the unfortunate property that with mixed numeric types, the equality comparison was not transitive (A=B and B=C did not guarantee A=C). Rather than live with this situation, Saxon 13 implements the resolution from the 4.0 specifications, whether or not XSLT 4.0 processing is enabled.