Both actually, well rather it’s used for any class that casts magic (mage, sage, probably shaman and monk too) and handles the looping animation the character has during a spell animation. (meaning how their robes/cape continue to flap while the spell happens)
As far as how it works, that’s a good question. My guess would be a shorthand way of handling the looping of 3-4 frames during the magic cast, but how it does that is a mystery. I imagine C47 handles that separately from the framedata, since it’s hard-coded perhaps there’s something else that runs the loop?
I know those frames in particular are not located in the framedata for standard animations, which is why it’s so hard-coded.
Thank goodness there’s a simpler way to add loops to custom animations in FEditor Adv at least!