Melta Weapons with [MELTA X] in their profile are known as Melta weapons. Each time an attack made with such a weapon targets a unit within half that weapon’s range, that attack’s Damage characteristic is increased by the amount denoted by ‘x’.
Heavy Weapons with [HEAVY] in their profile are known as Heavy weapons. Each time an attack is made with such a weapon, if the attacking model’s unit Remained Stationary this turn, add 1 to that attack’s Hit roll.