Table 1: Four classes of the importance grades.

GradeAction in tree revision

HighAttribute should be incorporated into the top several percentages of important decision nodes.

MediumAttribute can be incorporated into the decision nodes above the average importance.

LowAttribute may be an irrelevant attribute that is probably appended closer to the leaf node and later on pruned or be considered as a supporting attribute to others.

NoneAttribute is treated as noise and can be ignored.