The Interoperability Problem: Coalition Governance Translation at the C5ISR Edge

P8 established classification integrity at the object level; P9 established accreditation integrity at the node level. Both papers assumed a single, coherent governance regime — one classification taxonomy, one accreditation authority, one set of cross-domain enforcement rules — and developed substrate architectures for maintaining integrity within that regime under DDIL conditions. This assumption is operationally inadequate for coalition operations. Modern maritime, joint, and combined operations routinely require data exchange between nodes governed by different classification taxonomies, accredited by different national authorities, using CDS implementations from different vendors, and operating under different legal authorities that constrain what data may be shared and under what conditions. The interoperability problem is not the technical problem of getting packets across a heterogeneous network — protocol-level interoperability is a solved problem. The interoperability problem is the governance synchronization problem of exchanging state across a boundary where the two sides do not share a classification and accreditation regime. This paper argues that interoperability at the tactical edge is a governance translation problem before it is a technical exchange problem. A DTN bundle carrying SECRET//REL TO USA//FVEY data, correctly classified and correctly routed under US classification policy, may not be correctly handled by a Canadian node operating under Canadian classification authority — not because the Canadian node cannot receive DTN bundles, but because "SECRET//REL TO FVEY" has no direct Canadian equivalent, the releasability determination for this specific bundle under the bilateral information sharing agreement may require re-evaluation, and the Canadian node's accreditation authority is CANAD-DND, not the US DoD AO. The technical exchange is trivial. The governance translation is not. The paper develops four structural failure modes in protocol-first interoperability at the DDIL edge — classification taxonomy mismatch, accreditation regime incompatibility, CDS semantic divergence, and AI Supervisor model incompatibility — and proposes a governance translation architecture that uses the substrate primitives to maintain governance integrity across regime boundaries. The §6 Governor Application grounds this architecture in HGC³AE²: governance translation policy belongs to the H half; translation state cataloging belongs to the C³ half; translation boundary authentication and enforcement belong to the AE² half. This is Paper 10 of The Implications of Edge Degraded Ops — an 11-paper undecalogy on distributed state at the C5ISR edge under DDIL conditions. The frame paper is The Tactical Substrate; the load-bearing governance framework is HGC³AE² at the Degraded Edge. Rights envelope: Citation permitted with full attribution. No reproduction, redistribution, or derivative works without written permission. AI/ML training use disallowed. See the citation policy at https://nonsequitur.tech/pubs/citation-policy/ for the full rights envelope. Canonical site URL: https://nonsequitur.tech/white-papers/interoperability-problem/