Blue Club counts controls as one of the key indicators of the strength of a hand.
Unless specified otherwise, an Ace counts as 2 controls and a King counts as 1.
An initial positive response to the 1C opening shows responder's controls by steps.
Once a trump suit has been agreed either partner may use cue bids to show controls below game level without promising additional strength; where space permits, first round controls are shown ahead of second round controls. In this context, a void or A counts as a first round control, and a K or singleton counts as a second round control.