It was first found in World Heroes Perfect and is mostly characteristic of the KOF series from ’96 onwards.
It is similar to super armor, except that it acts like a block; only chip damage will be taken. Thus, it can be used like an attack and a block at the same time, it is still defenseless against the unblockable throw hitbox, and oftentimes it is subject to a guard crush.
It is found on many special moves for power characters like Ralf Jones, as well as for some quick, slender brawlers (especially Kusanagi Kyō and K′). It is also found on normal moves for a few unusual characters like Maxima and Anji Mito. Finally, there are some moves like Ryō Sakazaki’s “Jōdan Uke” and “Gedan Uke” that do not even have an attack hitbox (these two moves advance in particular block while advancing).