Status: PROPOSED · v0.1 DRAFT · not yet ratified by any standards body. This document is published for comment and as the basis for submission to a trade-finance standards body (e.g. ICC, BAFT). It describes a format, not a set of prices, and Mirror asserts no endorsement it has not received.
1. Why a standard, and why an open one#
Two banks can only reconcile a trade blindly if they band its value against the same table. That table — which price bands, which matching windows, which locator scheme, which tolerance, under which legal basis — is the one genuinely multi-party artifact in an otherwise bilateral protocol. Agreeing it ad hoc is a months-long negotiation and a miniature cold-start: the exact friction that has sunk cross-institution trade networks before.
An open, ratifiable corridor-table format converts that friction into a moat. When the format is a published standard, lighting up corridor N+1 is a countersignature rather than a committee, any conformant implementation interoperates, and no single vendor owns the definition. This document specifies that format. It deliberately does not specify any prices: the standard is the shape of the table; the values inside it are ratified by the participating banks, never by Mirror and never by this document.
Non-goals. This standard invents no prices, publishes no benchmark, and names no goods. A corridor table with nonsense edges produces nonsense bands — that is the ratifying parties' responsibility, checked by their governance, not by the format.
2. The corridor table object#
A corridor table is a canonical JSON object. Every field is load-bearing; a table missing or malforming any of them is invalid, never silently defaulted (fail-closed, in the AML direction — an unreadable table must never yield a clean reconciliation).
| Field | Type | Meaning |
|---|---|---|
product | string (ASCII) | The corridor's product/commodity label, ratified by the parties. Opaque to the operator. |
version | integer ≥ 1 | Monotonic version. A new version is a new table; bands never mutate in place. |
edges | array of distinct finite numbers, ≥ 1 | The band boundaries. Sorted canonically before use; duplicates are refused. |
corridor_id | string | Derived from edges, never trusted from a claim. If supplied, it must equal the derivation or the table is rejected. |
tolerance | integer ≥ 0 | The match-window width in bands, applied at the operator as a set union. Non-negative; out of range → invalid. |
windows | object | Per-role matching windows (how long each leg has to arrive). A missing or inverted window → invalid. |
locator_scheme | enum | One of the registered locator schemes, defining how the two banks derive the same opaque join key for a shipment. |
legal_basis | string | The basis for sharing the parties assert (e.g. a 314(b) registration, an AMLR Art. 75 arrangement). Asserted here; coverage is checked elsewhere. |
effective_from | timestamp | When the ratified table comes in force. Ratified ≠ in force; a table with a future effective time is frozen until then. |
valid_until | timestamp, optional | When the table stops judging (a time-bound corridor). Carried on the proposal, so it is ratified with the table. After it, a reconciliation naming the table is refused (table_expired) rather than judged under another version; a renewal is a new version. An unreadable value refuses the proposal — it never becomes an unbounded table. |
closed | boolean | Whether the table is the half-open range (first edge, last edge]. On a closed table a value outside that range commits markers that match nothing, so it can never clear; on an open one the outer bands run to zero and to infinity, and two legs both in the top band agree at any ratio. Anything but a boolean refuses the proposal. A new corridor must be closed. |
max_ratio | number > 1 | The match ceiling: the widest price ratio a clear on this corridor may stand for. A clear whose window is wider is held (match_ceiling). Only a closed table can meet a ceiling. A new corridor must carry one of at most 1.5, and its widest band at tolerance 0 must fit under it. |
reference | object, optional | A ratio corridor: the edges are a published ratio table (ratio-5, ratio-10, ratio-20) and each leg bands price ÷ R, where R is the exact median of a quorum of cited public figures. The object is { table, sources, quorum, max_spread, rule }: citations only, never a figure. Its id is rs: + SHA-256 of its canonical form. With reference, the edges must be exactly that table and closed must be true. See ratio corridors. |
2.1 corridor_id derivation#
corridor_id is a deterministic function of the sorted edges alone (SHA-256 over the canonical edge list). Two banks that independently hold the same edges derive the same id without coordinating a label — the id is how their commitments join, so it can never be a free-text claim. A table that carries a corridor_id inconsistent with its edges is refused outright: a table cannot claim one identity and band under another.
3. Ratification and the book#
A corridor table becomes authoritative only through quorum countersignature. A charter binding the table is endorsed by a quorum of at least two distinct ratifying members; a quorum of one is not a quorum. Endorsements fold deterministically into an append-only book — the corridor's constitution — so that years later a supervisor can ask "under exactly which table, ratified by whom, and when, was this trade reconciled?" and get a signed, offline-verifiable answer. History is preserved by construction; a ratified table is never edited, only superseded by a new version.
Lifecycle: proposed → ratified → in force → superseded/retired. Each transition is a signed event; the book folds them in order; nothing is mutated retroactively.
4. Interoperability and conformance#
The point of a standard is that an implementation built inside Bank A's core stack lands a leg in byte-identical commitments to the same leg banded by Bank B, or the blind reconciliation is comparing apples to noise. An implementation is conformant when it reproduces the reference commitment vectors for a given table exactly. Conformance earns a signed certificate; there is no partial pass. This lets the format spread through vendors who never integrate with Mirror directly — a vendor that emits conformant commitments to its own customers propagates the standard.
5. Honest boundaries of the standard#
- The table defines bands, not exact values. Reconciliation against it proves same-band agreement, never equality of prices.
- A ratified table encodes only what the parties agreed; a wrong table produces wrong bands, and the standard cannot tell. Table correctness is the ratifying parties' governance responsibility.
legal_basisis asserted, not established, by the table. Whether that basis actually covers a given exchange is checked outside the format.- This standard is a proposal. It has not been ratified by any standards body, and Mirror claims no such ratification.
6. Reference implementation#
A dependency-free reference implementation of table validation, corridor_id derivation, charter endorsement, the append-only book, and the conformance vectors is published with the protocol specification. Every construct in this document maps to a deterministic, individually-tested kernel; the reference is the normative tie-breaker for any ambiguity in the prose above.