Measurement of local bow:

Place the tempered glass upright on the turnover rack with the roller contacting surface facing outward. place a 300 mm straight ruler parallel to the edge at a distance of 25 mm from the edge of the glass. Measure the gap between the glass and the ruler with a feeler gauge. The maximum value is the local bow of the glass.

Measurement of edge kink:

Place the tempered glass on a workbench horizontally with the upper surface facing up and the leading (or rear) edge of the glass overhung by 50-100mm. Along the direction perpendicular to the leading  (or rear) edge of the glass, place a 300mm straight ruler against the glass with one end of the ruler aligned with the leading (or rear) edge of the glass. Measure the gap between the straight ruler and the leading (or rear) edge. This value is known as the edge kink of the glass. The edge kink usually occurs in an area 20mm away from the edge of the glass.