Classic is an arrow type option first used in pre-DDRMAX -Dance Dance Revolution 6thMIX- games. It is the same shape as a normal arrow except with a V-shaped snout on the back tip of the arrow. It was made into a usable arrow type option in DanceDanceRevolution X.
The Classic option was the only available arrow option.
The Classic option was added on DDR X as an unlockable arrow option, to celebrate the DDR series's 10th anniversary. In DDR X2 onwards, it is available by default.