I believe that entry makes the previously hardcoded defense penalty for planets moddable.
It means that an attacking ship will almost never miss a planet, but now modders can change the value of "almost".
The two entries before that have interesting implications; unmodded seekers have a +40 defense bonus, and a planet's weapons platforms have a +30 attack bonus.
[ August 15, 2002, 22:41: Message edited by: capnq ]