> ## Documentation Index
> Fetch the complete documentation index at: https://docs.attest.so/llms.txt
> Use this file to discover all available pages before exploring further.

# Schema Design

> Creating and using schemas on Stellar

## What is a Schema?

A schema defines the structure of attestation data. All attestations reference a schema.

## Creating a Schema

```typescript theme={null}
await client.createSchema({
  definition: 'struct KYC { bool verified; string level; u64 timestamp; }',
  revocable: true,
  resolver: undefined, // Optional: validation contract
  options: { signer }
});
```

## Schema Syntax

```
struct Name { type field; type field; ... }
```

### Supported Types

| Type     | Description     | Example         |
| -------- | --------------- | --------------- |
| `bool`   | Boolean         | `true`, `false` |
| `string` | Text            | `"hello"`       |
| `u32`    | Unsigned 32-bit | `42`            |
| `u64`    | Unsigned 64-bit | `1234567890`    |
| `i32`    | Signed 32-bit   | `-42`           |
| `i64`    | Signed 64-bit   | `-1234567890`   |
| `bytes`  | Binary data     | `0x1234...`     |

## Example Schemas

### KYC Verification

```
struct KYC { bool verified; string level; string provider; u64 expiry; }
```

### Professional Credential

```
struct Credential { string title; string issuer; u64 issuedAt; u64 expiresAt; }
```

### Reputation Score

```
struct Reputation { u32 score; string category; u64 updatedAt; }
```

## Generating Schema UID

Schema UIDs are deterministic based on definition + authority:

```typescript theme={null}
const schemaUid = client.generateSchemaUid({
  definition: 'struct KYC { bool verified; string level; }',
  authority: keypair.publicKey(),
  resolver: undefined
});
```

## Querying Schemas

```typescript theme={null}
// By UID
const schema = await client.getSchema(schemaUid);

// By wallet (schemas you created)
const { schemas } = await client.fetchSchemasByWallet({
  walletAddress: keypair.publicKey(),
  limit: 50
});

// Latest schemas
const latest = await client.fetchSchemas(100);
```

## Best Practices

1. **Keep it simple** - Only include necessary fields
2. **Use appropriate types** - `u64` for timestamps, `bool` for flags
3. **Consider revocability** - Set `revocable: true` for credentials that may need invalidation
4. **Version schemas** - Include version in name: `struct KYC_v2 { ... }`