I've always wondered (voyager and DS9 are both notorius for this....) During battle, as the ship takes damage and sparks are flying all over, you hear Tuvok, Nog or Reed yell out: "Hull integrity down to __ %!!" What does this mean exactly? If my hull intergrity drops to say 40%, does that mean my ship is physically full of holes? or is it something to do with the molecular structure of my hull being only 40% of what it was before whatever damged me? How would you gauge Hull Integrity in real-time besides basically knowing my hull is damaged and where the damage is? how does that translate to a percentage in real time?