> OS X is NOT "based" on FreeBSD. It is based on a BSD system,
> but it still uses the Mach kernel, all of which was
> inherited from NextStep.
>
> Jason

Luckily I'd clarified this in a later email.

OpenDarwin shares over a million lines of source with the FreeBSD 5.x
tree...
http://www.apple.com/macosx/features/unix/
http://images.apple.com/macosx/pdf/MacOSX_UNIX_TB.pdf

N.