Dirtside II: Local Air Defense.

I'm reading the book and I can see how Local Air Defense systemd can
engage
attacking aircraft.  My next question is back in the missile section. 
The
rules say that a Zone Defense system can engage any missile within 12
inches
and that a Point Defense System can engage missiles coming at the unit. 
The
rules also give the dice size for the attacks, however it provides
neither
for Local Air defense.	If you have any knowledge of how its supposed to
work, please let me know.
  Phil P.