Consequently,
Schedule I includes: "non-marketable narcotics"; these are illicit narcotics without current evidence-based medical benefit, e.g. heroin and all Ecstasy-type drugs.
Schedule II includes: "licit narcotic drugs, but not available as such on special prescription", e.g. narcotics which are used commercially for the manufacture of other products, particularly pharmaceuticals. These include, inter alia, delta-9-tetrahydrocannabinol (THC) and dexamphetamine.
Schedule III includes: "marketable narcotic drugs available on special prescription", these are all narcotic drugs which may be prescribed by physicians, dental surgeons and veterinary surgeons for medical purposes (e.g. opium, morphine and methadone).