Point defense in Vegastrike
Point defense systems in Vegastrike roughly correspond to anti-missile systems. While doing so is a bit of a misnomer insofar as the actual definition of point defense is much broader, we felt it more useful to split the other forms of primarily defensive armaments (which is what light anti-fighter weapons mounted on a capship really are) from the anti-missile armaments, which we have therefore been able to make purely defensive in their targeting behavior, and in general treat as special cases.
Basically, considering a spacecraft large enough to mount a few turrets as an element sufficiently special to warrant protection, then those turrets, if they are mounting defensive weaponry, correspond to the fixed installations present at such a site whose role is to defend that site.
General (Real life) definition
(DOD) The defense or protection of special vital elements and installations; e.g., command and control facilities or air bases.