I get the A/B/C thing... I was just throwing coil size into the mix, because I think that it is just as important to care and styling as other characteristics.
The difference between a pencil diameter and a coffee stirrer diameter is huge, imo. And as such, I believe it calls for another category...5. I consider myself a 5C, since I have very small coils, with no definition, even soaking wet/with product. And even have to be careful with my twist outs.