For the purposes of subparagraph 471.15(1)(b)(ii) of the Code, the following are dangerous or harmful substances or things that must not, without exception, be carried by post:
(a) gas that is so toxic or corrosive to humans as to pose a hazard to health;
(b) a thermally unstable substance that is likely to undergo a strongly exothermic decomposition;
(c) a substance that ignites or self - heats when in contact with air.