UXF (Unicity eXchange Format) is a content-addressable packaging format for storing and exchanging Unicity token materials — cryptographic containers carrying complete off-chain ownership histories including genesis records, state transitions, and inclusion proofs — across users, devices, and distributed systems such as IPFS. The core architectural mechanism recursively deconstructs tokens into a shared, flat element pool where every node at every depth of the hierarchy (token, transaction, inclusion proof, unicity certificate, seal, SMT path segment) is independently content-hashed and stored once; a token manifest maps each tokenId to its DAG root, and tokens are reassembled on demand by traversing child references. This design achieves deep deduplication across the full token pool: unicity certificates, nametag token subtrees, and SMT path segments shared between otherwise distinct tokens occupy a single DAG node referenced by multiple parents. Each element may participate in an instance chain in which newer instances carry a predecessor hash linking back to earlier ones, enabling three non-destructive evolution modes: representation re-encoding, proof consolidation (merging per-transaction proofs into compact SMT subtrees), and ZK proof substitution (replacing full transaction history with a succinct proof) — all without invalidating or removing prior instances. Every element header encodes both a representation version and a semantic version: semantic versions are fixed at creation and must never change, while representation versions may evolve, supporting mixed-version tokens where a v1 genesis coexists with v2 transactions in a single reassembled structure. The format is append-only by invariant — elements are immutable once committed. IPFS/IPLD alignment is structural rather than incidental, as the DAG node model maps directly onto CID-addressed IPLD blocks. Deliverables are a formal specification (CDDL/JSON Schema) and a TypeScript reference implementation covering ingest, assemble, merge, diff, verify, instance chain management, and IPLD-compatible DAG export.
UXF (Unicity eXchange Format) is a content-addressable packaging format for storing and exchanging Unicity token materials — cryptographic containers carrying complete off-chain ownership histories including genesis records, state transitions, and inclusion proofs — across users, devices, and distributed systems such as IPFS. The core architectural mechanism recursively deconstructs tokens into a shared, flat element pool where every node at every depth of the hierarchy (token, transaction, inclusion proof, unicity certificate, seal, SMT path segment) is independently content-hashed and stored once; a token manifest maps each tokenId to its DAG root, and tokens are reassembled on demand by traversing child references. This design achieves deep deduplication across the full token pool: unicity certificates, nametag token subtrees, and SMT path segments shared between otherwise distinct tokens occupy a single DAG node referenced by multiple parents. Each element may participate in an instance chain in which newer instances carry a predecessor hash linking back to earlier ones, enabling three non-destructive evolution modes: representation re-encoding, proof consolidation (merging per-transaction proofs into compact SMT subtrees), and ZK proof substitution (replacing full transaction history with a succinct proof) — all without invalidating or removing prior instances. Every element header encodes both a representation version and a semantic version: semantic versions are fixed at creation and must never change, while representation versions may evolve, supporting mixed-version tokens where a v1 genesis coexists with v2 transactions in a single reassembled structure. The format is append-only by invariant — elements are immutable once committed. IPFS/IPLD alignment is structural rather than incidental, as the DAG node model maps directly onto CID-addressed IPLD blocks. Deliverables are a formal specification (CDDL/JSON Schema) and a TypeScript reference implementation covering ingest, assemble, merge, diff, verify, instance chain management, and IPLD-compatible DAG export.