ok, im speaking from experience here:
i own an impulse with an i frame, if i went into a paintball store and asked for an electronic trigger for my impy, they would automatically assume i meant a trigger frame+board, as the board which has the small clicky bit that activates the solenoid is housed in the top of the trigger frame on the board,
all the trigger is , is a piece of metal, that bends upwards, hitting a small lever, which hits a small switch, which in turn, activates the solenoid which fires the marker basically. a trigger is merely a piece of metal/plastic/material, i will get a dictionary as you have pissed me off so much and get the meaning, here we go :
Trigger :small lever releasing a catch on a gun or machine; action that sets off a course of events.