Choose the role played by the primary and secondary cards when two memory cards are inserted in the camera.
Choose from Overflow (the secondary card is used only when the primary card is full), Backup (each picture is recorded to both the primary and secondary card), and RAW primary - JPEG secondary (as for Backup, except that the NEF/RAW copies of photos shot at settings of NEF/RAW + JPEG are recorded only to the primary card and the JPEG copies only to the secondary card).