transtornos due to uso of unknown or não especificado psychoactive substances are characterised by the padrão and consequences of psychoactive substance uso when the specific substance is unknown or não especificado. These categories may be used in clinical situations in which it is clear that the disturbance is due to substance uso but the specific class of substance is unknown. Once the relevant substance is identified, the disturbance should be recoded under the appropriate substance class.