Place a reference plane (such as a straight edge) on the table top face, trace a displacement gauge in the table moving range, and obtain the maximum value of displacement from the straight line that connects the start point and the end point. This value is defined as straightness.
The straightness has a vertical component and a horizontal component. The maximum value of each component is defined as the stage straightness.

An indicator is set up at the table so that it touches the perpendicular surface of the standard square, and then it is raised while measuring the displacement.
Displacement when moving from the starting point of one stroke end (displacement 0) to the opposite stroke end is defined as verticality.