To be honest...I'm not sure. He wrote a book in the late 90s, maybe it was around that time?
As for the 3d hair-typing category, well, I understand where the OP is trying to go with it. It's good to have people to identify with. I knew that those who identified as "4b" or "4c" were bound to have super-kinky hair like me. (Now the number doesn't matter so much; I can tell if your hair is kinky or not just by looking at it. Lol.)
However, it sounds weird to me. When I read the title, I was like, isn't all hair 3d? I'm pretty sure it's not 2-dimensional.