Refer to figure.
Some dangerous goods are identified as too dangerous to be carried on any aircraft. Some are forbidden in normal circumstances but may be carried with specific approval from the States concerned. Some are restricted to carriage only on all cargo aircraft, but most may be carried on both passenger and all-cargo aircraft, subject to meeting the required conditions.

Those restricted to all cargo aircraft are either in larger quantities than allowed on passenger aircraft or are forbidden on such aircraft. Their transport is permitted due to their being usually accessible in flight and to the ability of the flight crew to consider a greater range of actions in an emergency than is possible on passenger aircraft.

Except as otherwise provided in the TIs, packages of dangerous goods bearing the "Cargo Aircraft ONLY" label shall be loaded so that a crew member or other authorized person can see, handle, and, where size and weight permit, separate such packages from other cargo in flight.