psycofang2

it's any time an attack hits on an active frame other than it's first. the most common situation where this happens is on wakeup, because that's where the attacking player has the most control over when they get a move to connect. the idea is that you recover quicker because you don't have to sit through the rest of your active frames. so for example, hakumen's 5C has 2 active frames, 20 frames of recovery, and is a level 4 move so it inflicts 18 frames of blockstun. under normal circumstances, it puts you at -3. however, if you make it hit on the second active frame, you can recover just one frame faster than usual. like the article said, blockstun - recovery = maximum frame advantage. so in this case, 18 - 20 = -2, the maximum frame advantage in this situation.