— Assertions and Coverage
statements with action blocks
SystemVerilog
3.1a adds several new constructs and changes:
—      Definition and support of a compilation unit
—     
Packages
containing declarations such as data, types, classes, tasks and functions
—     
Separate
compilation support
—     
A
compilation-unit scope visible only within a compilation unit 
—      Removal of the $root global declaration
space from SystemVerilog 3.1