C.25:15.4 - Maintainability and evolvability

Maintainability or evolvability claims often drift into pure rhetoric. In C.25, they become usable only when the publisher separates:

• the declared scope of systems or change classes,
• the measurable slots (for example change lead time, defect reintroduction rate, restoration interval, review load),
• the enabling mechanisms (modularity rules, test harnesses, interface discipline),
• and the window or evidence conditions under which those measures were observed.

This is exactly the kind of quality family that looks scalar in speech but turns composite once the claim is made explicit.