Andrew once again furrowed his brow at the professor's question. He was really having a hard time remembering any specifics about the classification system, and was internally kicking himself for not studying harder. Despite being unsure, he'd never forgive himself if he didn't at least make an educated guess, and he did just that.

Raising his hand once more, he waited patiently for the professor to call on him, at which point he tentatively presented his answer:
"I'm afraid, professor, that I can't recall anything quite so specific, but if I remember correctly, when the original system was first created, it only had the 'Being' and 'Beast' categories." He paused for a moment as he collected his thoughts. "Soon after they started using this new system, enormous groups of ghosts who were not satisfied with their placement in the 'Being' category organized several protest floats - Ghost demonstrations outside the Ministry which eventually lead to the creation of the 'Spirit' category."

Taking a deep breath, Andrew crossed his fingers and hoped his answer had been good enough. "That sounds to me like a 'dispute over a definition' if I ever heard of one."