ATPG中test coverage和fault coverag

FAULT CLASS

fault的分类大致有两种：

UT(untestable) ：UU( Undetectable unuse) TI（ Undetectable tied） BL( Undetectable blocked ) RE( Undetectable Redundant)

TE(testable): DT(detected) PD(Possibly Detected) AU(ATPG Untestable) UD( Not Detected)

test coverage 

fault coverage