DOPI is how you answer Blackwood when an opponent overcalls partner's 4NT: Double shows zero key cards (or aces), Pass shows one, and each bid up the line shows one more. ROPI is the same idea when the opponent doubles 4NT: Redouble shows zero, Pass shows one. DEPO is the high-level version: Double shows an even number, Pass an odd number.
These are not system-specific. Pairs playing 2/1, SAYC or Acol use them with plain Blackwood and with Roman Key Card Blackwood alike. They need disclosure: in ACBL events, conventional calls this high in the auction usually get a delayed alert, so you explain them to the opponents when the auction is over.
How DOPI Works
Opponents who bid over 4NT are trying to take away your step responses. DOPI gives the steps back. You use the double and the pass as the first two steps, then continue with bids:
| Your call after 4NT - (overcall) | Plain Blackwood | RKCB (0314 order) |
|---|---|---|
| Double | 0 aces | 0 or 3 key cards |
| Pass | 1 ace | 1 or 4 key cards |
| First bid up | 2 aces | 2 key cards, no trump queen |
| Second bid up | 3 aces | 2 key cards with the trump queen |
After your double, partner can pass for penalties or bid on. After your pass, partner can double the overcall or bid the slam. Either way, the asker learns the count and keeps control.
Players who use 1430 responses often swap the first two steps so the order matches their normal replies: Pass then shows 0 or 3 and Double 1 or 4. Some call this PODI. Neither is better; the danger is two partners playing different versions.
Rule of ThumbDOPI: Double = 0, Pass = 1, then the steps. ROPI: Redouble = 0, Pass = 1, then the steps. With RKCB, the same calls mean 0 or 3 and 1 or 4.
ROPI: When They Double 4NT
Sometimes the opponent doubles 4NT, usually to suggest a lead or a sacrifice. You still have all your normal bids, plus two extra calls: pass and redouble. ROPI uses them as the first two steps:
| Your call after 4NT - (X) | RKCB (0314 order) |
|---|---|
| Redouble | 0 or 3 key cards |
| Pass | 1 or 4 key cards |
| 5♣ | 2 key cards, no trump queen |
| 5♦ | 2 key cards with the trump queen |
Many partnerships simply ignore the double and give their normal responses. That also works, and it is easier to remember. Pick one method and stick with it.
DEPO: When the Overcall Is Too High
If the opponents bid high enough, the steps run past your slam. Say hearts are trumps and the opponent overcalls 4NT with 6♣. The first bid up is 6♦ and the second is 6♥, so the replies use the whole six level and partner has no room to choose.
DEPO solves it with less detail: Double shows an even number (0, 2 or 4) and Pass shows an odd number (1, 3 or 5). Partner nearly always knows which number it is from the auction and his own hand.
A common agreement is DOPI when the overcall is at the five level and DEPO when it is at the six level. Some pairs use DEPO at every level because it never runs out of room. If the slam you are aiming at is lower than the steps need, switch to DEPO.
Example: DOPI After a Preemptive Overcall
East jumps to 5♠ over North's 4NT (RKCB). South passes to show one key card. North bids the slam.
North-South are vulnerable. North holds four aces and the ♥Q; South has the ♥K.
North opens 1♥ with 19 HCP. East makes a weak jump overcall of 2♠, and South shows a strong heart raise with the 3♠ cue bid. West, with four spades and no points, raises to 4♠ to make life hard. North asks with 4NT, RKCB in hearts (see what 4NT means in every system).
East bids 5♠, hoping to break the conversation. It does not work: South holds one key card, the ♥K, and passes to show it. North now counts all five key cards (four aces plus the trump king) and holds the trump queen too. North bids 6♥. North could look for the grand slam with 5NT, but a small slam is a fine result here.
What about doubling 5♠? East-West are not vulnerable. A double dummy solver gives East only five tricks in spades, so 5♠ doubled goes down six for +1400. Vulnerable 6♥ with its double dummy overtrick is worth +1460, so the slam is slightly better, and 7♥, which makes thirteen tricks double dummy, would be worth more still. Without DOPI, South could not show the key card under the 5♠ barrier, and North would be guessing.
Common Mistakes
- Treating the double as penalty. After 4NT, responder's double is a reply, not a penalty double. The penalty decision belongs to the asker.
- Mixing 1430 and 0314 orders. If you play 1430, agree whether Double means 0/3 or 1/4. Write it on your card.
- Using DOPI when steps go past the slam. If the second step is above your trump suit at the six level, you need DEPO.
- Forgetting the queen steps. With RKCB, the first bid up shows two key cards without the trump queen, the second shows two with it.
- Answering a double of 4NT with DOPI. When they double, the extra call is redouble, so play ROPI or ignore the double. A double is not even a legal call here: 4NT is already doubled.
The Full DOPI and ROPI Tree
For RKCB with 0314 responses (swap the first two lines if you play 1430):
| They overcall (DOPI) | They double (ROPI) | They bid at the six level (DEPO) | Key cards |
|---|---|---|---|
| Double | Redouble | Double | 0 or 3 (DEPO: 0, 2 or 4) |
| Pass | Pass | Pass | 1 or 4 (DEPO: 1, 3 or 5) |
| 1st bid up | 5♣ | - | 2, no trump queen |
| 2nd bid up | 5♦ | - | 2 with trump queen |
With plain Blackwood, read the rows as 0, 1, 2 and 3 aces. The same calls work when the opponents interfere over Gerber, if you play Gerber; agree it first.
Practice: DOPI and ROPI
Partner asks with 4NT (RKCB, 0314 in hearts). East bids 5♠. You play DOPI. Your call?
You play DOPI with RKCB (0314). Hearts are trumps. Partner bid 4NT and East bid 5♠. You hold the ♥K and the ♦A but not the ♥Q. What do you call?
Your hand:
Interference over Blackwood is rare, which is why it goes wrong when it happens. BridgeDummy's Bidding Room lets you bid deals against EPBot robots, alone or with a partner at /bidding/partner, so slam auctions with your own agreements come up in practice instead of at the table. To brush up on the asking side, read slam bidding.