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# IERC20PermitAllowed

Interface used by DAI/CHAI for permit

## Functions

### permit

```solidity theme={null}
  function permit(
    address holder,
    address spender,
    uint256 nonce,
    uint256 expiry,
    bool allowed,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external
```

Approve the spender to spend some tokens via the holder signature

This is the permit interface used by DAI and CHAI

#### 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| `expiry`  | uint256 | The timestamp at which the permit is no longer valid                          |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 valid secp256k1 signature from the holder along with `r` and `s` |
| `r`       | bytes32 | Must produce valid secp256k1 signature from the holder along with `v` and `s` |
| `s`       | bytes32 | Must produce valid secp256k1 signature from the holder along with `r` and `v` |