Smash directional influence

Smash directional influence, or SDI for short, is an advanced technique present in SSF2. It is performed during hitlag, which allows characters to escape combos (in multi-hits), move closer to a wall to tech, or minimally move away from the blast zone.

How to perform
To SDI, simply press any button on your directional controls OR your C-stick buttons in the direction you want to go. This will cause your character to move in whichever direction is desired. Doing SDI with both sticks will ultimately move your character further than if only one stick was used. This is referred to as Dual-Stick SDI, and it is commonly used for SDI'ing Isaac's down-B, Black Mage's Stop, and other situationally specific moves.

Trivia

 * In the game's code, the sdiDistance parameter exists to modify how far SDI moves the character(s) when hit by that specific move.