1. An area or object that has a flat perpendicular surface or any thing or any action that can be associated directly or indirectly with this in an appropriate context. Your hands represent the surface itself, or you move your hand (or hands) as if you were moving your hand over the surface. Signers use this to show the location, orientation or extent of flat surfaces such as a wall, fence, barrier or partition. With minimal or no context, signers will assume you mean a wall.