# IERC20PermitAllowed

### Functions <a href="#functions" id="functions"></a>

#### permit <a href="#permit" id="permit"></a>

Approve the spender to spend some tokens via the holder signature.

*This is the permit interface used by DAI and CHAI.*

```solidity
function permit(
    address holder,
    address spender,
    uint256 nonce,
    uint256 expiry,
    bool allowed,
    uint8 v,
    bytes32 r,
    bytes32 s
) external;
```

**Parameters**

| Name      | Type      | Description                                                                      |
| --------- | --------- | -------------------------------------------------------------------------------- |
| `holder`  | `address` | The address of the token holder, the token owner.                                |
| `spender` | `address` | The address of the token spender.                                                |
| `nonce`   | `uint256` | The holder's nonce, increases at each call to permit.                            |
| `expiry`  | `uint256` | The timestamp at which the permit is no longer valid.                            |
| `allowed` | `bool`    | Boolean that sets approval amount, true for type(uint256).max and false for 0.   |
| `v`       | `uint8`   | Must produce a valid secp256k1 signature from the holder along with `r` and `s`. |
| `r`       | `bytes32` | Must produce a valid secp256k1 signature from the holder along with `v` and `s`. |
| `s`       | `bytes32` | Must produce a valid secp256k1 signature from the holder along with `r` and `v`. |

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