The ATA Security feature set is described in NIST Special Publication 800-88 Revision 1. ATA Security applies to both SED and non-SED drives. The ATA Security command set specifies a SECURITY ERASE UNIT command that erases all accessible user data by writing all binary 0s or 1s. There is an option for ENHANCED ERASE mode that erases all reallocated user data and writes a vendor specific data pattern. Although all data in the user-accessible space is completely erased, some data such as the NAND block mapping tables may still physically reside on the SSD. Support and use of the built-in ATA security commands vary by SSD.