Table 2. The grading system of the wood samples attacked by the subterranean termites (ASTM D 1758-06)

Grade no.	Description
10	No attack, 1 to 2 small nibbles permitted
9	Nibbles to 3% cross-section
8	Penetration 3% to 10% of cross-section
7	Penetration 10% to 30% cross-section
6	Penetration 30% to 50% cross-section
4	Penetration 50% to 75% cross-section
0	Failure

Adapted from American Society for Testing and Material (2006) with permission of ASTM International.