FSA: reading 24, page 254: q4 and q9: pension expense and NI difference, economic, reading, benefit, between

soddy1979

about pension expense, contribution and NI adjustment.
does Q4 and Q9 in nature the same?
Q4 adjust NI by the amount (difference between economic pension expense and periodic expense)*(1-tax) down
for Q9, looks like this is how to get CFO from NI, so add net periodic benefit cost back and deduct contribution, why net periodic benefit cost is treated as non-expense item? Thanks.