> For the complete documentation index, see [llms.txt](https://docs.cheqd.io/product/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cheqd.io/product/studio/trust-registries/dtc/tao-to-subtao.md).
# TAO -> SubTAO
A **Trusted Accreditation Organisation (TAO)** can extend trust further down the hierarchy by accrediting **Sub-Trusted Accreditation Organisations (SubTAOs)**. These SubTAOs may then be authorized to issue further **Verifiable Accreditations** or **Verifiable Attestations**, subject to defined constraints.
The Verifiable Accreditation should include:
| Field | Description | Example |
| ------------------ | --------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------ |
| Issuer | DID of the TAO | did:cheqd:testnet:a2b675de-33d0-4044-8183-0d74f210cceb |
| Subject | DID of the SubTAO that is being accredited | did:cheqd:testnet:e66a9416-d03e-4ced-95e3-07af16e25bc5 |
| Credential Subject | A set of structured permissions around what credentials the SubTAO is accredited to issue, and in which jurisdiction. | See below |
| Terms of use | A set of policies setting out the scope of Trust Chain for Relying parties to validate against. | See below |
## Permissions
The `credentialSubject` section outlines what the SubTAO is accredited to do — including supported credential types, relevant schemas, and jurisdictional constraints.
```json
"credentialSubject": {
"id": "did:cheqd:testnet:e66a9416-d03e-4ced-95e3-07af16e25bc5",
"accreditedFor": [
{
"schemaId": "did:cheqd:testnet:8ea036da-f340-480d-8952-f5561ea1763c/resources/b10146d7-0d0f-41e0-8ee3-c76db64890be",
"types": [
"VerifiableCredential",
"VerifiableAccreditation",
"VerifiableAttestation",
"VerifiableAccreditationToAccredit"
],
"limitJurisdiction": "https://publications.europa.eu/resource/authority/atu/FIN"
}
]
},
```
Whereby:
| Field | Description |
| ----------------- | ----------------------------------------------------------------------------------------------------------------------- |
| schemaId | Schema of the Verifiable Accreditation that the SubTAO is accredited to issue themselves |
| types | Types of Credential that the SubTAO is accredited to issue |
| limitJurisdiction | (Optional) Permission that the TAO can set to limit the jurisdictional scope of the credentials issued in the ecosystem |
## Policies
The `termsOfUse` field contains an **AccreditationPolicy**, which points back to both the parent accreditation and the original root authorization. This maintains traceability through the full trust chain.
```json
"termsOfUse": {
"type": "AccreditationPolicy",
"parentAccreditation": "did:cheqd:testnet:8ea036da-f340-480d-8952-f5561ea1763c/resources/18de60ec-bed1-42e5-980c-601c432bc60b",
"rootAuthorization": "did:cheqd:testnet:8ea036da-f340-480d-8952-f5561ea1763c/resources/18de60ec-bed1-42e5-980c-601c432bc60b"
}
```
Whereby:
| Field | Description |
| ------------------- | --------------------------------------------------------------------------------- |
| type | Must be `AccreditationPolicy` |
| parentAccreditation | The DID URL of the Accreditation issued by another TAO or the Root TAO to the TAO |
| rootAuthorization | The DID URL of the Root of Trust Verifiable Authorization |
### Example of fully formed Accreditation
The example below shows a Verifiable Accreditation that is issued by an TAO to a SubTAO, granting permission to issue further accreditations under a defined schema and policy chain.
```json
{
"@context": [
"https://www.w3.org/2018/credentials/v1",
"https://schema.org/schema.jsonld",
"https://veramo.io/contexts/profile/v1"
],
"issuer": {
"id": "did:cheqd:testnet:b003df6f-ec8e-48dd-9a2b-7011c5cf0a5e"
},
"type": [
"VerifiableCredential",
"VerifiableAccreditationToAccredit"
],
"issuanceDate": "2024-08-07T02:08:30.000Z",
"credentialSubject": {
"accreditedFor": [
{
"schemaId": "https://resolver.cheqd.net/1.0/identifiers/did:cheqd:testnet:b003df6f-ec8e-48dd-9a2b-7011c5cf0a5e?resourceName=VerifiableAccreditation&resourceType=JSONSchemaValidator2020",
"types": [
"VerifiableCredential",
"VerifiableAccreditation",
"VerifiableAttestation",
"VerifiableAccreditationToAccredit"
]
}
],
"id": "did:cheqd:testnet:6af412d7-2f04-4e12-a424-e6719db487ad"
},
"termsOfUse": {
"type": "AccreditationPolicy",
"parentAccreditation": "did:cheqd:testnet:8ea036da-f340-480d-8952-f5561ea1763c/resources/18de60ec-bed1-42e5-980c-601c432bc60b",
"rootAuthorization": "did:cheqd:testnet:8ea036da-f340-480d-8952-f5561ea1763c/resources/18de60ec-bed1-42e5-980c-601c432bc60b"
},
"proof": {
"type": "JwtProof2020",
"jwt": "eyJhbGciOiJFZERTQSIsInR5cCI6IkpXVCJ9.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.CrEirG-Yki2HCfY6GjNR_Oqx0ZV6uJr1NPpTTLnVWfG1Q9R3YASj7IyEZ3FtVGRmdSNhQ9v2pmPijVxeBnwPAg"
}
}
```
For all Verifiable Accreditations, the accreditations are stored as DID-Linked Resources (DLRs), linked to the DID of the Accreditor. This means that the Accreditations are publicly available, fully DID resolvable and are signed by the `authentication` keys within the DID Document of the Accreditor.
DID-Linked Resources
Learn about cheqd's approach to implementing DID-Linked Resources
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