A bid showing a balanced hand with 12-14 HCP in the Kaplan-Sheinwold system, or 13-15 in Precision. A suit bid, then rebid of 1NT shows 15-17 HCP. Stayman, transfers are used the same as with the strong NT opening.
A bidding convention is an agreement between two players on a different meaning of a bid in the card game bridge. These agreements are made so that partners can more quickly determine which contract, with both their cards, they can win together. Often, conventions are forged together into one, which is then called a bidding system.