> ## Documentation Index > Fetch the complete documentation index at: https://docs.droplinked.com/llms.txt > Use this file to discover all available pages before exploring further. # Schema D — Cross / peer attestation > On-chain reference for the peer-trust schema. Any registered entity attests any other entity with a 0-100 trust score and short basis — the reconciler closes the loop on disputes by mirroring registry status onto the attestation envelope. Schema D is the **reconciler / cross-attestation** — peer trust expressed on chain. Unlike Schemas A (operator-issued brand identity), B (lender-issued credit verdict), and C (lender-issued repayment history), Schema D is open to **any registered entity attesting any other registered entity** with a 0-100 trust score and a short free-text `basis`. This is the dispute-loop surface. When a merchant disputes a credit-risk verdict, when a service provider cross-attests inventory custody, when a business buyer attests a merchant's reliability — those are all Schema D rows. The reconciler closes the loop by mirroring **current** registry status onto every ACTIVE Schema D attestation every 6 hours, so verifiers can decide whether to honor an attestation issued by a party whose standing has since changed. | | | | -------------------- | ---------------------------------------------------------------------------------------------- | | **Schema name** | `CrossAttestation` | | **EAS revocable** | yes | | **Expiry semantics** | none | | **Issued by** | Any registered `merchant` / `lender` / `business-buyer` / `service-provider` | | **Subject** | Any registered `merchant` / `lender` / `business-buyer` / `service-provider` | | **MCP tool** | [`verify_cross_attestation`](/agentic/mcp-server), [`get_trust_dossier`](/agentic/mcp-server) | | **Verifier API** | `GET /v2/attestations/cross/subject/:rootUid` and `GET /v2/attestations/cross/issuer/:rootUid` | ## Network & UIDs | Network | EAS contract | Schema UID | Explorer | | ------------ | -------------------------------------------- | -------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Base mainnet | `0x4200000000000000000000000000000000000021` | `0xb076cf65e9547678fe0e0c5ff010b504e7133ffe03977dc5fad2598723e5554e` | [basescan](https://basescan.org/address/0x4200000000000000000000000000000000000021) · [easscan schema](https://base.easscan.org/schema/view/0xb076cf65e9547678fe0e0c5ff010b504e7133ffe03977dc5fad2598723e5554e) | | Base Sepolia | `0x4200000000000000000000000000000000000021` | resolve via `chain` field on `/v2/attestations/cross/*` | [sepolia.basescan](https://sepolia.basescan.org/address/0x4200000000000000000000000000000000000021) | EAS registry version: **v1.4.0**. ## Field reference ABI schema string: ``` string issuerRootUid, string subjectRootUid, uint8 trustScore, string basis, uint256 attestedAt ``` | Field | Solidity type | Semantic | Mutability | | ---------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------- | | `issuerRootUid` | `string` | Attester anchor. Form: `":"` where `entityType ∈ {merchant, lender, business-buyer, service-provider}`. | immutable per attestation | | `subjectRootUid` | `string` | Subject anchor. Same form as `issuerRootUid`. | immutable per attestation | | `trustScore` | `uint8` | 0-100. Semantically **not** canonicalized by Droplinked — a 70 from a lender and a 70 from a business-buyer are not directly comparable. Always combine with `basis` and `issuerEntityType` when consuming. | immutable per attestation | | `basis` | `string` | Free-text basis for the score. Capped at 512 bytes (\~\$0.08 mainnet gas). | immutable per attestation | | `attestedAt` | `uint256` | Unix seconds. Block-mined issuance time. | immutable | EAS envelope fields: | Envelope field | Type | Semantic | | ---------------- | --------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- | | `uid` | `bytes32` | Attestation UID. | | `schema` | `bytes32` | Schema UID (above). | | `attester` | `address` | Issuer's on-chain signing wallet. For `service-provider` issuers this is the partner's operator wallet (currently `ACTIVE` in `ServiceProviderRegistry`). | | `recipient` | `address` | Subject's wallet or `0x0` (subject identity is in `subjectRootUid`). | | `time` | `uint64` | Mirrors `attestedAt`. | | `expirationTime` | `uint64` | `0` (no expiry). | | `revocationTime` | `uint64` | `0` if active. | | `revocable` | `bool` | `true`. | | `data` | `bytes` | ABI-encoded payload per the schema string above. | ## Registry-status mirror (`attestorCurrentStatus`) The reconciler sweeps every 6 hours and mirrors the **current** issuer registry status onto every ACTIVE Schema D row. This is how Schema D closes the dispute loop: ```json theme={null} { "status": "ACTIVE", "attestorCurrentStatus": "SUSPENDED", "attestorCurrentStatusAt": "2026-06-14T01:00:00Z" } ``` For `service-provider` issuers, this mirrors `ServiceProviderRegistry`. For other issuer types (merchant, lender, business-buyer), this remains `null` until those registry lookups are wired into the reconciler. The reconciler **never auto-revokes**. A Schema D attestation issued by a service provider that has since been **SUSPENDED** (e.g., contract terminated, custody dispute) is still on-chain ACTIVE — the chain has no opinion. Verifier policy decides whether to honor it. The MCP `get_trust_dossier` tool exposes the mirror in its envelope. ## How Schema D closes the loop on disputes The 4-axis trust fabric is open on the inputs (lenders write B + C, operators write A) but the **resolution loop is also open**: a disputing party writes a Schema D attestation referencing the disputed record. Two patterns are observed in production: 1. **Counter-attestation** — a merchant disputes a Schema B verdict by minting a Schema D row with `subjectRootUid = "lender:"`, `trustScore` low, and `basis` citing the disputed UID. Subsequent verifiers see both records and apply their own policy. 2. **Service-provider attestation** — a WMS partner (e.g., Stor'd) cross-attests inventory custody. This is independent evidence feeding back into the lender's Schema B re-underwrite at next term. The `service-provider` issuer class is registered in `ServiceProviderRegistry`; the partner's signing wallet must be `ACTIVE` for the attestation to be honored. The reconciler doesn't take sides. It only ensures that **at read time**, a verifier sees the current registry standing of every party in the dispute graph. ## Read via Droplinked API By subject — "what has anyone said about this entity": ```bash theme={null} curl -s "https://apiv3.droplinked.com/v2/attestations/cross/subject/merchant:6a0001a08692425bd9fd571b" | jq . ``` By issuer — "what has this entity said about anyone": ```bash theme={null} curl -s "https://apiv3.droplinked.com/v2/attestations/cross/issuer/lender:crediblex-uae" | jq . ``` ```json theme={null} { "found": true, "chain": "base", "count": 2, "attestations": [ { "attestationUid": "0x…", "schemaUid": "0xb076…554e", "issuerEntityType": "service-provider", "issuerEntityId": "stord-prod", "issuerWallet": "0x…", "subjectEntityType": "merchant", "subjectEntityId": "6a0001a08692425bd9fd571b", "trustScore": 88, "basis": "12-month custody relationship, 0 inventory disputes, $4.2M of throughput", "attestedAt": "2026-06-14T12:00:00Z", "status": "ACTIVE", "attestorCurrentStatus": "ACTIVE", "attestorCurrentStatusAt": "2026-06-14T18:00:00Z" } ] } ``` ## Read via viem (TypeScript) ```ts theme={null} import { createPublicClient, http, parseAbi, decodeAbiParameters } from "viem"; import { base } from "viem/chains"; const EAS = "0x4200000000000000000000000000000000000021" as const; const SCHEMA_D = "0xb076cf65e9547678fe0e0c5ff010b504e7133ffe03977dc5fad2598723e5554e" as const; const client = createPublicClient({ chain: base, transport: http() }); const easAbi = parseAbi([ "function getAttestation(bytes32 uid) view returns (tuple(bytes32 uid, bytes32 schema, uint64 time, uint64 expirationTime, uint64 revocationTime, bytes32 refUID, address recipient, address attester, bool revocable, bytes data))", ]); const uid = "0x…"; // UID from /v2/attestations/cross/* const att = await client.readContract({ address: EAS, abi: easAbi, functionName: "getAttestation", args: [uid], }); if (att.schema !== SCHEMA_D) throw new Error("not a Schema D attestation"); const [issuerRootUid, subjectRootUid, trustScore, basis, attestedAt] = decodeAbiParameters( [ { name: "issuerRootUid", type: "string" }, { name: "subjectRootUid", type: "string" }, { name: "trustScore", type: "uint8" }, { name: "basis", type: "string" }, { name: "attestedAt", type: "uint256" }, ], att.data, ); const isActive = att.revocationTime === 0n; console.log({ issuerRootUid, subjectRootUid, trustScore: Number(trustScore), basis, attestedAt, isActive }); ``` ## Read via ethers (TypeScript) ```ts theme={null} import { JsonRpcProvider, Contract, AbiCoder } from "ethers"; const EAS = "0x4200000000000000000000000000000000000021"; const SCHEMA_D = "0xb076cf65e9547678fe0e0c5ff010b504e7133ffe03977dc5fad2598723e5554e"; const provider = new JsonRpcProvider("https://mainnet.base.org"); const eas = new Contract( EAS, [ "function getAttestation(bytes32 uid) view returns (tuple(bytes32 uid, bytes32 schema, uint64 time, uint64 expirationTime, uint64 revocationTime, bytes32 refUID, address recipient, address attester, bool revocable, bytes data))", ], provider, ); const uid = "0x…"; const att = await eas.getAttestation(uid); if (att.schema.toLowerCase() !== SCHEMA_D) throw new Error("schema mismatch"); const [issuerRootUid, subjectRootUid, trustScore, basis, attestedAt] = AbiCoder.defaultAbiCoder().decode( ["string", "string", "uint8", "string", "uint256"], att.data, ); console.log({ issuerRootUid, subjectRootUid, trustScore, basis, attestedAt }); ``` ## Read via Cast (Foundry) ```bash theme={null} cast call 0x4200000000000000000000000000000000000021 \ "getAttestation(bytes32)((bytes32,bytes32,uint64,uint64,uint64,bytes32,address,address,bool,bytes))" \ 0x…UID… \ --rpc-url https://mainnet.base.org cast abi-decode \ "x(string,string,uint8,string,uint256)" \ 0x…data-field… ``` ## Indexer access (EAS GraphQL) * Base mainnet: [https://base.easscan.org/graphql](https://base.easscan.org/graphql) * Base Sepolia: [https://base-sepolia.easscan.org/graphql](https://base-sepolia.easscan.org/graphql) **"All Schema D attestations issued BY this wallet"** — issuer-side enumeration: ```graphql theme={null} query IssuedBy($wallet: String!) { attestations( where: { schemaId: { equals: "0xb076cf65e9547678fe0e0c5ff010b504e7133ffe03977dc5fad2598723e5554e" } attester: { equals: $wallet } } orderBy: { time: desc } take: 100 ) { id time revocationTime recipient data } } ``` **"All Schema D attestations targeting this subject"** — for fast subject-side enumeration with already-decoded fields, use the Droplinked API (`GET /v2/attestations/cross/subject/:rootUid`). EAS GraphQL has no native index on the encoded `subjectRootUid` string. ## Trust assumptions A Schema D attestation is authoritative if and only if: 1. The on-chain `schema` matches the mainnet UID above. 2. The on-chain `attester` wallet maps to a currently `ACTIVE` registered entity. For `service-provider` issuers, check `ServiceProviderRegistry` (Droplinked-side admin lookup) — the verifier API exposes the mirror via `attestorCurrentStatus`. 3. `revocationTime == 0`. 4. The semantic interpretation of `trustScore` is the consumer's responsibility — Droplinked does **not** canonicalize a comparable scale across `issuerEntityType` classes. Always read `basis` and `issuerEntityType` together with the score. For non-`service-provider` issuer classes (merchant, lender, business-buyer), the reconciler does not yet wire registry status into `attestorCurrentStatus`; it will return `null`. Cross-check the issuer directly against [`/v2/lenders/:lenderId`](/api-reference/public/lender-registry) (for lender issuers) or the merchant verifier path until those mirrors land. ## Related * [Trust Fabric overview](/concepts/trust-fabric) * [Schemas overview](/api-reference/public/eas-schemas/overview) * [Schema B — Credit-risk attestation](/api-reference/public/eas-schemas/schema-b-writer) (the most-disputed surface) * [Schema C — Repayment-history attestation](/api-reference/public/eas-schemas/schema-c-reader) * [`get_trust_dossier` MCP tool](/agentic/mcp-server) — multi-axis composite read