37.18.1.1 SLC/MLC Write Operation with Spare Enable Bit Set

When PMECCFG.SPAREEN is set, the spare area of the page is encoded with the data stream of the last sector of the page. This mode is entered by setting PMECCTRL.DATA. When the encoding process is over, the redundancy is written to the spare area in User mode. PMECCTRL.USER must be set.