http://www.nasva.go.jp/mamoru/english/2000/e00f042.html
2.Evaluation of the 6 ranks
AAA:The risk of serious injury to both the head and the chest is very low.
AA:The risk of serious injury to either the head or the chest is very low and the risk of serious injury to the other is low.
A:The risk of serious injury to both the head and the chest is low.
B:The risk of serious injury to either the head or the chest is low and there is somewhat of a risk of serious injury to the other.
C:There is somewhat of a risk of serious injury to both the head and the chest.
D:There is a risk of serious injury to either the head or the chest or to both of them.
2.Evaluation of the 6 ranks
AAA:The risk of serious injury to both the head and the chest is very low.
AA:The risk of serious injury to either the head or the chest is very low and the risk of serious injury to the other is low.
A:The risk of serious injury to both the head and the chest is low.
B:The risk of serious injury to either the head or the chest is low and there is somewhat of a risk of serious injury to the other.
C:There is somewhat of a risk of serious injury to both the head and the chest.
D:There is a risk of serious injury to either the head or the chest or to both of them.