(cattāri sammā-padhānāņi, catvāri samyak-pradhāņāni, 四正勤) is
- to decrease (existing) bad karma
- to not create (unborn) bad karma
- to start (unborn) good karma
- to increase (existing) good karma.
The Fourfold Right Severance/Deletion (cattāri sammā-pahāņāni, catvāri samyak-prahāņāni, 四正断) is misinterpretation or mis-attribution of the former, because there are 3) and 4) (starting and increasing, not only severing/deleting).