28:16 · These ideograms were put into use at the beginning of the 1970s in medical bulletins, prescriptions, and drug catalogues. The uppermost means danger for habituation and is applicable to amphetamines (drugs that stimulate the central nervous system) and drugs with the opposite effect, like the opiates morphine and heroin and similar drugs (narcotics).
    The lower sign means weak stimulants or depressants, with some risk for habituation. This sign applies to barbiturates and similar drugs, i.e. the most common sleeping pills, tranquilizers (e.g. Valium), and sedatives.