some times I think the debate of whether a J-10 prototype is of B or C variant is a moot point. The Chinese military or Chengdu never gave out any designation of variants. They continuously add improvements to the airframe, only people in the internet forums use B and C to distinguish different batches, so what is the definition of B and C, or D...? Who is to define them? In my opinion, nobody in the internet has the authority. So I'd suggest we concentrate our discussion on the specific improvements, changes, not the letters.