Confused about a file with no links

[Joe Smith]

In trying to snoop on a process doing (apparently) nothing, I found this:

$ /usr/etc/pstat -i | awk 'NR==2 || $7 == 0'
  ILOC   IFLAG  IDEVICE   INO   MODE NLK  UID  SIZE/DEV VFLAG CNT SHC EXC TYPE
 f0b8f90    R     7,  0  1765 100600   0  131       247         1   0   0 VREG

As the 'NLK' field is supposed to be the number of links to the file (and
NLK agrees with ls for other files which I could find directory entries
for) I am curious as to what a file with no links is and what conditions
create them.

 Joe Smith
 University of Pennsylvania                    jes at mbio.med.upenn.edu
 Dept. of Biochemistry and Biophysics          (215) 898-8348
 Philadelphia, PA 19104-6059