The Convention divides drugs into four groups, or schedules, in order to enforce a greater or lesser degree of control for the various substances and compounds. Opium smoking and eating, coca leaf chewing, cannabis resin smoking and the non-medical use of cannabis are prohibited. The 1972 Protocol to this Convention calls for increased efforts to prevent illicit production of, traffic in and use of narcotics as defined by the Convention, while highlighting the need to provide treatment and rehabilitation services to drug abusers.