Opponents interfere over our 1NT opening

After a Penalty DBL

• RDBL: 5+ in a minor, weak. Partner must bid 2C.
• 2C (Stayman): Maybe 4+4+ in majors in a weak hand. Partner has only 3 possible responses.
• 2D/H: Transfers
• Pass: Weak, no 5+ suit, no 4-4 in majors. Partner may RDBL to initiate a scramble or bid a suit with 5+ cards.
• All other bids are unchanged

After a Non-penalty DBL the system stays unchanged

After a level-2 over-call showing explicitly only 1 suit

• New suit at level 2: competitive, non forcing
• DBL: Negative (Stayman)
• Pass over an artificial over-call followed by DBL: Business
• Cue-bid at level 2 (If possible, i.e. after a transfer intervention): Take-out, no indication about stoppers. May hide a limit club 1-suiter, but typically has values for 2NT.
• 3NT: With stopper
• 2NT/3C/D/H: transfer. Tranfser to opponent's suit asks for stopper.

After a 2-suited over-call showing explicitly both suits

• New suit: Competitive
• DBL: Business if over-call is natural (Negative otherwise)
• 2NT: Invitational
• Lower cue-bid: Shows the lower of the other 2 suits
• Higher cue-bid: Shows the higher of the other 2 suits

After 2NT with a 2-suiter (usually the minors)

• Pass: The equivalent of a Negative DBL or a Competitive bid or a Pass
• DBL: business interest and also initiates stopper investigation
• All other bids are as above

After a Natural Over-call at level 3

• DBL: Negative
• New suit: game forcing
• 3NT: sign off
• 4NT: QST

After a DBL of our Stayman 2C

• RDBL: Let’s play!
• Pass: club stopper
• RDBL: restarts the usual sequence
  
• Other: no club stopper, same as without intervention
  

After an over-call of our Stayman 2C

• DBL: Business
• 2H/S: 4 cards
• Cue-bid 3D: 4+ cards in both majors
• 3C/D: Good 5+ suit
• Pass: Otherwise. If next opponent passes, responder bids:
  • DBL: Business
  • 2H/S: Competitive
  • 3H/S over 2D: Smolen
  • Cue-bid: Asks for stopper
  • 3C/D: Natural, forcing
  • 2/3NT: Limit

After a DBL of our transfer bid (showing the suit)

• Pass: 2 cards in partner's suit
• "accept" transfer: sign-off
• 2/3NT: stopper
• RDBL: no stopper
• Other bid: fit

After an over-call of our transfer bid

• Pass: The usual bid. After opponent’s pass follows:
• DBL: Negative
• New suit: Competitive
• Accept own transfer: Competitive
• NT: Limit
• Cue-bid: Take-out
• Jump shift: 5+5+, game values
• DBL: Negative
• Other: Fit