It's kind-of both, the AT is called the Red Spin and it is the result of abusing a glitch. When you use the Red Spin from side B initially, if it clanks with another attack then it gets "stored". The next time you use side B Link will continue the attack with no startup. It is doable in mi-air as well. The application of this is that you can purposely use it to clank, store it for later, and then surprise the foe with it when they least expect it since it comes out so fast.