The chemicals in the Inventory of Chemicals Subject to Supervision and Control refer to chemicals that can be used as chemical weapons, or chemicals that can be used as precursors for the production of chemical weapons, or chemicals that can be used as primary ingredients for the production of chemical weapons, or specified organic chemicals excluding explosives and pure hydrocarbons. The chemicals in the Inventory of Chemicals Subject to Supervision and Control are divided into four categories, the first category: chemicals that can be used as chemical weapons; the second category: chemicals that can be used as precursors for the production of chemical weapons; the third category: Chemicals that can be used as primary ingredients for the production of chemical weapons; the fourth category: specified organic chemicals excluding explosives and pure hydrocarbons.