Packaging, installation, and licensing changes
XSLT 2.0 implementation
XSLT 3.0 implementation
XQuery 1.0 implementation
XQuery 3.0 implementation
XQuery 3.1 implementation
XPath 3.0 implementation
XPath 3.1 implementation
Functions, operators, and data types for XPath 3.1
XML Schema 1.0 implementation
XML Schema 1.1 implementation
Serialization
Saxon extensions to the W3C XSLT/XQuery specifications
S9API interface
Changes specific to .NET
Command line interfaces
Extensibility mechanisms
JAXP interface (transformation, XPath, schema processing)
System Programming Interfaces
Internal changes
Optimizations and performance improvements
Streamed processing of input documents
Support for DOM and other external tree models
Localization (natural language support)