AFSSI-5020 is the USAF Cryptologic Support Center purging standard from 1996. This deletion method first overwrites the target data area with the fixed value (0x00), then with the fixed value (0xff), and then with a randomly selected constant. Finally, at least 10% of the drive is read to verify the overwrites. [1] Obsolete: AFFSSI-5220 was superseded by AFFSSI 8580 on 7 Jan 2011 by order of AFI 33-112 (paragraph 8)