In example 1 below the responder's first bid was 1
.
She might have a long Diamond suit and a 4 card Major. In this case she
wants to CHECK to see if opener also has a 4 card Major. To do this responder
rebids 3 
. This bid
is called CHECK BACK STAYMAN. In example 1, the 3
bid is not support for partners 1
opening bid, but a request that partner bid a 4 card Major. In this case
the DMZ opener bids her 4 card Major, or if none the 3 .
This is just like regular Stayman over a 2 NT opener. The use of CHECK
BACK STAYMAN in example 1 allows the DMZ opener to bypass the bid of 1 
or 1 
over partner's
1 response. The
direct jump to 2 NT does not deny 4 cards in either one or both of the
other Major suits.
| 1. OPENER
RESPONDER
1
1
2 NT
3 |
In
example
2 below the responder's first bid was a 1 .
Responder might have 4 cards in both Hearts and Spades. (she bids 1 or
"up the ladder" with 4/4 in the Majors.) Then the subsequent 3
(CHECK BACK STAYMAN) bid by the responder gives the DMZ opener a chance
to show 4 cards in the other Major (Spades). The responder is hoping partner
has a 4 card Spade suit. (Then game is 4.)
If there is a Major suit fit then responder goes to game in that suit.
If no fit, then responder bids 3 NT. This use of CHECK BACK STAYMAN in
example
2 allows the DMZ opener to bypass a bid of 1
over partner's 1
Response. The direct jump to 2 NT does not deny 4 cards in the other Major
suit.
| 2. OPENER
RESPONDER
1
1
2 NT
3 |
Also
in example 2 above, responder might have a 5 card Heart suit and
is asking if opener has 3 card support. (This is similar to the New Minor
Force.) Note: a 3
rebid by the DMZ opener over 3 shows
3 Hearts. For if opener had 4 Hearts, she would have jumped to 4
immediately over responders first bid of 1
and not bid 2 NT.
In example 3 below responder could have 5/5 or 5/4 in the majors
and is looking for a major suit fit. Again she uses CHECK BACK STAYMAN.
A 3 rebid by DMZ
opener shows 3 Spades. A 3
bid shows 4 Hearts
| 3. OPENER
RESPONDER
1
1
2 NT
3 |
Note: in all three of the above examples the 3
bid is artificial and not necessarily a show a suit nor support a partners
1 opening bid. The
3 Club bid is always CHECK BACK STAYMAN. Responder need not pass partner's
game bid. She can make a slam try or bid the slam directly.
* The DMZ is a hand that falls between a 1 NT opener and a 2 NT opener. The bidder shows this type of hand by jumping in No Trump