ADDI analysis shows three copybooks with identical field definitions for a customer record. What optimization should be applied?

Think of it like working hands-on with IBM mainframe systems — the answer here is 'Retain all three copybooks because each calling program may require independent versioning'. Merging redundant copybooks into one canonical definition ensures wca4z generates a single Java class for the customer record, eliminating duplication and simplifying the resulting Java object model. On real mainframe exams, this concept comes up repeatedly so make sure you have it locked in.