Abbreviated DX.
Dexterity factors in movement, initiative and tasks requiring dexterity, eye-hand coordination, or fine motor control, including using missile weapons and guns.
Maneuvering during movement is actually a function of the Movement Stat, which is partially derived from DX.
A character’s base movement rate is Dice+DX in feet/second. This can be further modified by the Movement Stat - which seems really weird until you consider that centaurs and wheeled robots are possible as characters. But if your character walks on two legs, it’s Dice+DX.
Creatures lose 1 dice of default DX for every 2 dice of Size.