This chapter discusses using the ABAQUS Scripting Interface to write user scripts. ABAQUS makes every attempt to be backward compatible and can execute most ABAQUS Scripting Interface scripts from previous versions of ABAQUS. However, backward compatibility is not guaranteed beyond several versions of ABAQUS, and it is recommended that you upgrade your commands to the most recent version. A complete list of the ABAQUS Scripting Interface commands that have changed is included in Summary of ABAQUS Scripting Interface changes between Version 6.5 and Version 6.6 in the ABAQUS Scripting Reference Manual. This chapter provides an overview of the following enhancements: