1D Opening bid & Responses

   

Requirements:

5+ card Diamond suit denies any 5+ card Major suit - as then the opening would be either 3C (both red suits) or 2D (rebid 3D shows D's +S's)
10+ HCP
7 1/2 LTC maximum

Alternative openings that always take precedence:

2NT     21-22 Balanced - may be 4 or 5 cards
2C       23+ Balanced OR 5+ D's & <= 3 1/2 LTC
2D :     19-20 Balanced OR 5+-5+ in D & S
3C¦D:   5+-5+ redsuits or Majors.

Structural conditions

Longest suit held.

Partner's Responses 1D - ?

Opener's Rebids 1D - 1Ma

1S                                  4 card Spade suit
2Ma                               Fit - shows 4 card.
2C                                 4 card Natural
1N                                 12-16 Balanced. 2C Crowhurst inquiry available - Beta standard - regardless of 1NT opening strength!
J2NT                              17-18 Balanced. Invitational. Denies a fit
Splinter(4C or 3'Ma)      Shows 4 card support and a shortage in Clubs or the other Major
Jnew suit(3C or 2'Ma)    (15)16+ HCP A 2-3 card short suit with ideally 2 top honours. Forcing. Shows a single suited Diamond  hand
2D                                 6 card suit. 10-14
JD                                  6+ card suit 15+HCP

Opener's  after 1D - 1NT -  (Responder has no singleton¦void)

P                              To play
2D                           12-(15), 6 card suit, single suited - with 6-4 show 2nd suit on 1st rebid

2C                           4-5 card suit,     Note: if opener has a 6 card club suit 1C is mandatory even with a 5 card in any other suit.
2¦3NT                     Natural, balanced limit bids
3D                           15+HCP, quality 6+ card suit single suited hand
JZ(new suit)              (15)16+ Shows a Short suit (1) 2-3 cards with top controls - Never a void a singleton Ace is acepted.

Responder's Rebids 1D-Y(1Ma or 2C) - New suit(Z):  (Technically Forcing)

Responder's rebids 1D-any(OPP)-2¦3¦4 D's

The stronger 2D response is forcing, see Inverted minors

Responder's rebids 1D-any(OPP)-1N

Shows modest values 5-9HCP and may be passed.
A 6 card Diamond suit can be rebid
There is danger in bidding 2C or 2Ma (probably a 4-3 fit)