Frequent Twos

2D to 2S shows the suit bid and the a suit above witb 4/4 shape or better. 2S = spades and diamonds
5-10 points, rule of 15 (both suit lengths + point total > 14).

Responses = bid next higher suit to ask for higher suit. Responder corrects to higher suit if necessary. (e.g., if 2D opened, responder bids 2H to ask for higher suit. Opener passes or bids 2S to show 4 spades).