Honor Doubles and Redoubles
Also known as Rosenkranz (Re)Doubles.
After responder bids over partner's overcall, advancer can make a double or redouble to show at least Ax or Kx in over-caller's suit and about 6 or more points.
The implications are that a pass, free bid, or any raises deny those holdings (Ax or Kx). Examples:
Opp Partner Opp You
1C 1H Double(neg) Re-double = at least doubleton heart headed by Ace
or King
p = no possible bid
free bids = denies the Ace or King of hearts
heart raises = whatever point counts you've agreed
on, but denies the Ace or King of
hearts
Opp Partner Opp You
1H 1S 2D Double = at least doubleton spade headed by Ace or
King
p = no possible bid
free bids = denies the Ace or King of spades
spade raises = denies the Ace or King of spades
Reverse Rosenkranz Doubles
This is where the meanings of the double and raises are reversed. Thus a double denies the Ace or King, and a raise shows it.