Canape

1-level suit openings and responses follow the Canape style of naming the main suit on the second round; the first named suit may not be the longest or the best.

Opening requirements

Hands with at least 1.5 defensive tricks and no more than 7 losers (notionally 12+ points) qualify for a normal or strong opening.

Unbalanced hands which do not qualify for a special opening are bid according to the canape principle.

Big Hands
1C
17+ HCP with an unidentified 5+ card suit, 18-20 or 23+ balanced, 25+ any; typically 5 or fewer losers
2D
17-24 HCP, any 4-4-4-1
2NT
21-22 HCP, balanced.
Other Opening Hands
1D
12-16HCP, Qxx or better; canape is used, so this may not be the main suit.
1H
12-16HCP, 4+ cards; canape is used, so this may not be the main suit.
1S
12-16HCP, 4+ cards; canape is used, so this may not be the main suit.
1NT
16-17HCP balanced, or 12-15 exactly 3-3 in the majors and 4-5 Clubs.
2C
12-16HCP, good 6+ Clubs or a strong hand with 5+ Clubs and a second suit.
3C
12-16HCP, long & powerful Clubs, at least one gurard outside; 7-8 playing tricks

Canape

When dealing with 2-suited hands, the general principle is that the main suit is named on the second round.

2-suited hands are divided into strong and normal hands.

Strong hands have a solid 5+ or semi-solid 6+ card suit and a playable second suit, 15-16 HCP and typically 5 losers or less.

Strong Hands

Strong hands are further divided into hands where the main suit is Clubs, hands where the secondary suit is Clubs, and hands where neither suit is Clubs.

Strong hand, Neither suit is Clubs
Open the second suit, and plan to reverse or jump to the main suit on the second round.
Strong hand, Main suit is Clubs
Open 2C, preparing to show the second suit in response to a relay or in the course of the auction.
Strong hand, Second suit is Clubs
Open the main suit, planning to jump in Clubs on the second round
Normal, Balanced Hands 16-17HCP
Open 1NT.
Normal 2-suited Hands
Open the higher ranking suit, planning to rebid the longer suit (which may be the same).
Normal 1-suited Hands (Not Clubs)
Open the suit, planning to rebid the suit or no trumps.
Normal 1-suited Hands (Clubs)

With powerful Clubs, at least one guard outside & 7-8 playing tricks, open 2C.

If the Club suit is at least AQ9xxx, KQT9xx or so, open 2C.

If the hand has 3 good Diamonds in it (Qxx or better), open a convenient 1D.

If the hand is precisely 3-3 in the majors with 4 or 5 Clubs, open a conventional 1NT.

Defensive Openings
2H|S
7-11HCP, single suited hand no better than KQxxxx and no worse than QT9xxx, 0-3 controls, doesn't meet opening requirements.
3D|H|S
According to the rule of 2 & 3 with no more than 1 defensive trick outside the main suit and no more than 2 Aces
3NT
A running 7-card minor with no more than a Q outside