Which ADDI report is most useful for understanding overall portfolio complexity before planning transformation effort?

Think of it like working hands-on with IBM mainframe systems — the answer here is 'The RACF report showing which users have access to each program load library'. The program inventory report provides metrics such as program count, total lines of code, and copybook reuse that teams use to size modernization effort and prioritize which programs to transform firs. On real mainframe exams, this concept comes up repeatedly so make sure you have it locked in.