instant trigger input?

I am interested in hooking up hood and trunk pin switches to my Clifford Matrix "instant trigger input". The description in my manual says "This input will respond to a negative input with an instant trigger." I understand that instant trigger means there's no warning, just an immediate siren blast, but i don't understand the negative input. Does this just mean that when that input shorts to ground (when the pin switches close), the alarm is triggered? Is it really that simple?

yes is that simpleHouston,TX

"The two most common elements in the universe are H+ and stupidity" (Ellison).