Trial Bids

When  responder supports opener's suit at the 2 or 3 level, the new suit inserted by opener at the minimum level is called trial bid..

 If responder supports your major,  a new suit by you shows responder your uncontrolled suit, and asks responder to bid 4 of your major if she has less then three loser in that suit..

If responder supports your minor,  a new suit by you shows responder your control on that suit, and asks responder if she can bid 3 NT..

Trial bid after support for major..	Trial bid after support for minor.
K Q 10 4 3 A K J A 9 7 6 5   A 9 6 9 7 4 Q 10 7 5 K 9	A 9 6 Q 4 A Q 10 9 7 5 K 9   10  A J  8 K J 8 6 2 10 7 6 5
W N E S Pass 1 S Pass 2S Pass 3C (Trial) Pass 4S Pass Pass Pass ---	W N E S Pass 1 D Pass 2D Pass 2S (Trial) Pass 3 NT Pass Pass Pass --
Here responder has less then three losers in club suit so she bids 4S.. If she had more then two losers she would bid 3S..	Since responder has control on other suits (heart and Club)  she can bid 3 NT.. If she did not have control on other suits she would bid 3 D...