Described here is an extension to the 2 over 1 bidding method when opener in 1st or 2nd seat opens a normal one club. A bid by responder of one diamond is artificial, shows 12+ points and is game forcing.

1 Club/1 Diamond : DocFox 

Topics:

• Basics
• Major suit fits
• After 1C - 1D - 2NT
• Pass short of game
• Fewer than 12 points
• First re-bids
• Quiz 1:  Both majors
• Quiz 2:  6 clubs
• Quiz 3:  Opener has clubs and diamonds
• Quiz 4:  Sample hands
• Common bridge phrases