1 pass (zeroed)
1 pass (pseudo random data)
should be added.
Cheers,
Steve
CC already provides both, in effect. The single pass for both Wipe Free Space and Drive Wiper is I believe zeroes. Whilst it might look like zeroes all data passes through many scrambling or coding routines before being written to disk. Strings of zeroes or ones are never written to disk. So you have both zero - to the user - and pseudo random - in actuality.
I haven't been able to establish whether this practice is applicable to SSD's, possibly not, but it certainly applies to all hard disks.