freebsd security - Sep 2007 - Why are most audit events apparently non-attributable?

So I'm exploring AUDIT and have this in /etc/security/audit_control:

dir:/var/audit
flags:lo,fd
minfree:20
naflags:lo
policy:cnt
filesz:0

I tell auditd to reread the config file with audit -s but no file
deletion events are logged.

I change the config file to:

dir:/var/audit
flags:lo
minfree:20
naflags:lo,fd
policy:cnt
filesz:0

I type audit -s and am immediately flooded with 20 kilobytes worth
of audit records about file deletions.

What I don't understand is why these file deletions are non-attributable?
Surely if I sit there touching and removing files, the events should be
very cleary attributed to me? Even more strange is that the events look
like this:

header,130,10,unlink(2),0,Sat Sep 29 20:48:46 2007, + 957 msec
path,/var/tmp/vi.recover/vi.zhcey0
attribute,600,root,wheel,126,24774,98340
subject,-1,root,wheel,root,wheel,78355,0,0,0.0.0.0
return,success,0
trailer,130

To me, that looks like the event was attributed to 'root', so why does
it only appear when using 'naflags' ie. non attributable events?

Perhaps I misunderstand something fundamental.

--
dc