Controlled Substance Registration (CSR) is a state-authorized license that allows practitioners to prescribe controlled substances (i.e., medication). Some states have different names for this registration, such as Controlled Dangerous Substance Registration (CDSR) or Bureau of Narcotics and Dangerous Drugs Registration (BNDD). Many states require this license in addition to the standard license and Drug Enforcement Administration (DEA). In these cases, the order in which the licenses must be granted is: State license. CSR license. DEA certificate.