Software Testing: What is the name of new feature testing in maintenance process?

In software maintenance process, after a new version is builded, there comes software maintenance testing.

In extent of software maintenance testing, it is done;

• Confirmation Testing, for fixed defects


• X testing, for new features


• Y testing, for modifications of existing features


• Regression Testing, to ensure that the changes not introduced new defects.

Please fill in the blanks, what is X and Y Testing?