Correct contract bridge / by E.V. Shepard ; including the official Laws of contract bridge adopted by the Whist Club, New York, and by all the leading clubs in America.

8o CORRECT CONTRACT BRIDGE
to be an informatory (subsequent) double. In the
first case you hope that partner may be able to respond with a major declaration; in the second case
you hope that partner can bid spades, and intend to
shift to no-trump if partner bids a heart.
A A io 5 2 KJ I03 4 AQJ6 O 5
A AIO5 2 v5 4 AQJ6 O KJIo3
An opening bid of a major suit, made on a hand
where rebidding strength chiefly lies in side suits,
justifies a rebid in case an opponent bids one of your
strong side suits, but if the opposing bid comes in
your weakest side suit the subsequent double should
be employed, as you cannot afford to be ruffed when
you are rather short of trumps, unless your partner
holds at least normal trump support. Either hand
shown below calls for an opening bid of i-Heart;
in case an opponent bids i-Spade you may rebid
hearts with the first hand, but the second hand obligates employing the double.
A QJ63 I' AKJ73 4 5 0 KQJ
A 5 t) AKJ73 4 QJ63 0 K QJ
With either hand the natural opening lead will
be spades; the first hand will not be called upon to
ruff the third round of that suit, thus conserving its
trumps; the second hand will be forced to trump
the second round of spades, as the hand contains
only five trumps and lacks a side ace, trumps cannot
be spared to ruff and still leave enough to pull down
opposing hearts, unless its holder is certain that his
partner has at least normal trump length,