by Silvertron » Sun Jun 24, 2012 12:35 am
As far as I can tell it means either/both. I've made steel with same q wrought and charcoal, fueled with lower q blocks, and got lower q steel.
I'd also guess most people use nice q blocks as fuel to make their nice q steel, not charcoal, which isn't so tough really, given how common q100+ trees (and thus sale of q100+ tree seeds) are by now.