The written request serves to initiate the RDAP application and should prompt an interview with either the institution’s RDAP Coordinator or a drug treatment specialist (DTS), or, if a prisoner is housed at a facility that does not offer the RDAP, a member of the Psychology Services staff.To qualify for RDAP, one must, inter alia, have at least 24 months or more remaining to serve; present a verifiable, documented pattern of substance abuse or dependence within the 12-month period preceding arrest on the underlying offense; have no serious mental or cognitive impairment precluding full program participation; be halfway house eligible (which precludes participation by removable non-U.S. citizens); and sign acknowledgment of program responsibilities.Section 3621 is silent with respect to how determinations about whether a prisoner has “a substance abuse problem” are made. And, while 28 C.F.R. §550.53(b) establishes criteria, in practice Program Statement 5330.11 controls. Staff reviews each program applicant’s PSR before scheduling an interview to ascertain whether the applicant meets the diagnostic criteria for abuse or dependence indicated in the Diagnostic and Statistical Manual of the Mental Disorders, Fourth Edition, (DSM-IV).