This document discusses limitations and objectives regarding dangerous goods transportation by air. It defines limitations as goods that are too dangerous to carry on aircraft or can only be carried on cargo aircraft. The objectives are to identify goods that are forbidden, permitted as cargo, or excepted from regulations. It also covers dangerous goods in excepted and limited quantities, as well as state and operator variations. The main types of dangerous goods are listed as forbidden, to be sent as cargo, or acceptable. Hidden dangerous goods and those carried by passengers or crew are also addressed.