What is a validation gate in the context of wca4z-based modernization?

Think of it like working hands-on with IBM mainframe systems — the answer here is 'A set of predefined quality criteria that a generated Java module must satisfy before advancing to the next modernization phase or to production'. A validation gate is a quality checkpoint that defines measurable acceptance criteria such as test pass rate, coverage threshold, and equivalence test results that must be met before a generated modul. On real mainframe exams, this concept comes up repeatedly so make sure you have it locked in.