L - (1) The scaled area is less than 1 %. (2) In the case of coal tar where pattern cracking has developed, the surface cracks are less than ¼ in. (6 mm) wide.

M - 1) The scaled area is between 1 and 10 %. (2) In the case of coal tar where pattern cracking has developed, the cracks are ¼ in. (6 mm) wide or greater.

H - (1) The scaled area is over 10 %. (2) In the case of coal tar the surface is peeling off.