Trialbids is a convention after the sequence 1H -2H / 1S -2S
The opener make an invitational bid in a suit to describe his hand.
LFT= Long suit trialbid. Shows a poor sidesuit (at least three small) an request for help.
The responder should bid game with strength in the suit (also with shortness and 4+trump).
KFT = Short suit trialbid. Shows a void or a singleton in the suit.
The responder should bid game if he has no wasted values in the suit.
1H -2H
2S : Request partner to bid 2NT. A start bid to show KFT.
2NT: LFT in S
3C : LFT in C
3D : LFT in D
3H : To play.
1H -2H -2S -2NT
3C :KFT in C
3D :KFT in D
3H :KFT in S
1S -2S
2NT: Request partner to bid 3C . A start bid to show KFT.
3C :LFT in C
3D :LFT in D
3H :LFT in H
3S : To play.
1S -2S -2NT-3C
3D :KFT in D
3H :KFT in H
3S :KFT in C