Papers 57 and 58 established the Frame Continuity Condition (FCC) and derived identity tolerance δ_F from the distinction between F_constitutive and F_operational. The determination problem for δ_F was resolved by grounding it in the constitutive layer of Frame. The present paper addresses the next problem: how is F_constitutive identified? We argue that F_constitutive is determined not by content but by function within LP’s integration architecture. A Frame property is constitutive if and only if its removal or inversion forces a reconstitution of the system’s integration architecture — not a recalibration within it. This criterion is structural, non-metric, and intersubjectively checkable. We formalize the distinction between constitutive and operational drift, address boundary cases, and show that ambiguous intermediate cases are not a weakness of the criterion but the expected structural signature of the Transmutation threshold.