The Constraint and the Enactment — Paper 59 of X: What Δ > 0 Claims, and What It Does Not

This paper draws a line between two kinds of quantity in physics and engineering: exact rules — conservation laws, quantization conditions, definitions, counts — and the measurements, transitions, and physical processes that occur under them. It argues that exactness belongs to the rule and never to the occurrence, that every real measurement and every real physical process carries an irreducible nonzero tolerance, and that treating a measured quantity as exact is a recurring and correctable methodological error. The distinction is familiar to metrology and to shop-floor practice — a datum is exact by role while the feature dimensioned from it carries a tolerance — and the 2019 SI redefinition applied the same split at the level of the base units. This paper states the rule explicitly, applies it to conservation laws and symmetry-protected quantities, and sets out the scope of the claim and its limits, including an epistemic status table separating confirmed observational claims from structural proposals. It also documents a pre-registration and audit protocol: locking interpretive choices in a timestamped record before the relevant data exists, declaring an indeterminate zone alongside every pass-or-fail threshold, and prohibiting redefinition after observation.