Documentation changes
Packaging, installation, and licensing changes
XSLT 3.0 implementation
XSLT 4.0 implementation
XQuery 3.1 implementation
XQuery 4.0 implementation
XPath 4.0 implementation
Functions, operators, and data types for XPath 3.1
Functions, operators, and data types for XPath 4.0
Serialization
Saxon extensions to the W3C XSLT/XQuery specifications
Saxon SQL extension instructions
S9API interface
Changes specific to .NET
Extensibility mechanisms
JAXP interface (transformation, XPath, schema processing)
System Programming Interfaces
Optimizations and performance improvements
Handling of source documents
Localization (natural language support)