> For the complete documentation index, see [llms.txt](https://docs.sign.global/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sign.global/for-builders/index-1/npm-sdk/usage/schemas.md).

# Schemas

## Types

### Schema (Onchain)

| Name          | Type                       | Description                                                                                                                                                              |
| ------------- | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| name          | `string`                   | Schema name.                                                                                                                                                             |
| description?  | `string`                   | Schema description.                                                                                                                                                      |
| revocable?    | `boolean`                  | Whether Attestations that adopt this Schema can be revoked.                                                                                                              |
| maxValidFor?  | `number`                   | The maximum number of seconds that an Attestation can remain valid. 0 means Attestations can be valid forever. This is enforced through `Attestation.validUntil`.        |
| hook?         | `address`                  | The contract address of the hook for this schema.                                                                                                                        |
| registrant    | `address`                  | The wallet address of the user that registered this schema.                                                                                                              |
| dataLocation? | `DataLocationOnChain`      | Where `Schema.data` is stored. See `DataLocation.DataLocation`.                                                                                                          |
| data          | `SchemaItem[]` or `string` | The data format defining this schema's data structure. When `dataLocation=ONCHAIN`, data is `SchemaItem[]`, when `dataLocation=ARWEAVE or IPFS`, data is id of the data. |

### Schema (Offchain)

| Name          | Type                   | Description                                                                                                                                                       |
| ------------- | ---------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| name          | `string`               | Schema name.                                                                                                                                                      |
| description?  | `string`               | Schema description.                                                                                                                                               |
| revocable?    | `boolean`              | Whether Attestations that adopt this Schema can be revoked.                                                                                                       |
| maxValidFor?  | `number`               | The maximum number of seconds that an Attestation can remain valid. 0 means Attestations can be valid forever. This is enforced through `Attestation.validUntil`. |
| dataLocation? | `DataLocationOffChain` | Where `Schema.data` is stored. See `DataLocation.DataLocation`.                                                                                                   |
| data          | `SchemaItem[]`         | The data format defining this schema's data structure.                                                                                                            |

## Usage

### Registering a Schema

```ts
async function createSchema(
  schema: Schema,
  options?: { getTxHash?: (txHash: `0x${string}`) => void }
): Promise<SchemaResult>;
```

#### Parameters

| Name     | Type                  | Description                    |
| -------- | --------------------- | ------------------------------ |
| schema   | `Schema`              | The schema being registered.   |
| options? | `CreateSchemaOptions` | Options for creating a schema. |

#### CreateSchemaOptions

| Name                 | Type                                | Description                                                                                                           |
| -------------------- | ----------------------------------- | --------------------------------------------------------------------------------------------------------------------- |
| delegationSignature? | string                              | The user's delegate signature for creating a schema on their behalf. Call `delegateSignSchema` to get this signature. |
| getTxHash?           | ``(txHash: `0x${string}`) => void`` | An optional callback that immediately returns the transaction hash.                                                   |

#### Example

```typescript
const res = await client.createSchema({
  name: "Example",
  data: [{ name: "name", type: "string" }],
});
```

### Retrieving a Schema

```ts
async function getSchema(schemaId: string): Promise<Schema>;
```

#### Parameters

| Name     | Type     | Description                                     |
| -------- | -------- | ----------------------------------------------- |
| schemaId | `string` | The ID of the schema we are trying to retrieve. |

#### Example

```typescript
const res = await client.getSchema("0x3e");
```

### Delegating On-chain Schema Registration via ECDSA

```ts
async function delegateSignSchema(
  schema: OnChainSchema,
  options: DelegateSignSchemaOptions
): Promise<SchemaDelegationSignature>;
```

#### Parameters

| Name    | Type                        | Description                              |
| ------- | --------------------------- | ---------------------------------------- |
| schema  | `OnChainSchema`             | An on-chain schema.                      |
| options | `DelegateSignSchemaOptions` | Options for delegate signing the schema. |

#### DelegateSignSchemaOptions

| Name               | Type                |                                                                                                                                |
| ------------------ | ------------------- | ------------------------------------------------------------------------------------------------------------------------------ |
| chain              | `EvmChains`         | The EVM chain you are targetting.                                                                                              |
| delegationAccount? | `PrivateKeyAccount` | The signer account that signs the message. See `viem/accounts`. If this is null, a signer from `window.ethereum` will be used. |
| rpcUrl?            | `string`            | Optional RPC URL.                                                                                                              |
| walletClient?      | `WalletClient`      | Optional `WalletClient` from viem to use for transactions.                                                                     |


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