Vertical Speed Conservation Conservation or VSC Conservation (VSCC for short), also known as Edge Grinding Angle Drift or EGAD (though this is a misnomer), is a glitch which lets Mario conserve stored vertical speed (VS) as a platform moves under him. By punching off the edge of a platform as it's moving, Mario remains in the punching action for 1 frame while the platform catches up to him. Since the platform is now under him, he continues his punching animation as if nothing happened. In the case of a rotating platform, this allows Mario to turn relative to the platform while maintaining stored VS, since he will be airbone and therefore not rotate for 1 frame while the platform does.
VSCC was originally thought of as an A Button Challenge strategy for Stomp on the Thwomp in 2 A presses. It would be used to change Mario's angle on the Tick Tock Clock hand while preserving VS to launch onto the Thwomp. However, it was discovered that with optimal straining, VSCC was unnecessary.