I would guess a nail gun that has to be placed then trigger pulled for each shot.
as opposed to holding the trigger down and bumping the nose of the gun for repetitive shots
The term usually refers to nail guns designed specifically for nailing metal connectors, such as Simpson straps and hangers. The nails need to be shot exactly into a hole in the metal.
I have a Bostich Framing Nailer with an interchangeable positive placement tip. It comes in handy since lot of hangers require 16d nails. I also have a Strap Shot for shooting Tico nails, it fits in much smaller spaces.