A.19.CN:Close - Closing perspective

A.19.CN makes comparability operational: a one-page CN-Spec, a registry for edition, status, supersession, and deprecation records, explicit relations and receiving-use claims for cross-local reuse, and a checklist plus harness for audit. It remains tool-agnostic and keeps every reading tied to its characteristic and scale editions, bearer, comparison basis, scope/window, evidence, and intended use.