OEBitVector OEBitVectorSub(const OEBitVector &a,
const OEBitVector &b)
The OEBitVectorSub function returns the Boolean difference of two
OEBitVectors. This function returns an OEBitVector where
each bit is set only if that position is set in the first operand and clear
in the second, i.e. a & b. The result will have the same
number of bits as the larger of the two operands. This function is identical
to the '-' operator of two OEBitVectors.