Since there were many lithium batteries which were not shown on the NOTOC that were loaded on the aircraft as cargo without the captain knowing he had such cargo, and these may have been the cause of recent aircraft accidents, a new Section IB had been installed in PI 965 and PI 968. The main intent of the introduction of Section IB was to have the airline make an acceptance check and enter such items on the NOTOC to alert the flight crew. Shipments of Section IB were subjected to a dedicated acceptance check and were obligated to enter into the NOTOC. Shipments of Section II on the other hand do not require acceptance check nor need to show on the NOTOC.
The two sections are totally independent of each other, and therefore APIO is out of the question, neither is Overpack. Although it does state in Section II of PI 965 and PI 968 that as long as they do not react dangerously with each other, Section II can be overpacked with other dangerous goods or non dangerous goods. Thence however if so done, how can the airline make a meaningful acceptance check? Since Section IB had been introduced to enhance safety, in order to achieve the intended level of safety, it is obvious that overpacking Section IB with Section II must be discouraged.