above board

If card players keep their hands above the table (the board), other players can see what they are doing.

源于纸牌游戏。如果玩牌者将手放在桌上，其动作就会被其他玩牌者看得一清二楚。

legal and honest; in a legal and honest way

合法而坦诚(的);开诚布公(的);公开(的)(多用于商业中，形容交易公平合理)

Don't worry, the deal was completely above board.

别担心，交易是完全合法的。

Why should there be any fear if everything is fair and square and above board?

如果一切都是公平公开公正的，为什么还要担心呢?