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# ERC721Permit

ERC721 with permit

Nonfungible tokens that support an approve via signature, i.e. permit

## Variables

### bytes32 PERMIT\_TYPEHASH constant

The permit typehash used in the permit signature

*Developer note: Value is equal to keccak256("Permit(address spender,uint256 tokenId,uint256 nonce,uint256 deadline)");*

## Functions

### DOMAIN\_SEPARATOR

`function DOMAIN_SEPARATOR() public view returns (bytes32)` view public

The domain separator used in the permit signature

**Returns:**

| Name | Type    | Description                                               |
| ---- | ------- | --------------------------------------------------------- |
| \[0] | bytes32 | The domain separator used in encoding of permit signature |

### permit

`function permit(address spender, uint256 tokenId, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external payable` payable external

Approve of a specific token ID for spending by spender via signature

| Name     | Type    | Description                                                                       |
| -------- | ------- | --------------------------------------------------------------------------------- |
| spender  | address | The account that is being approved                                                |
| tokenId  | uint256 | The ID of the token that is being approved for spending                           |
| deadline | uint256 | The deadline timestamp by which the call must be mined for the approve to work    |
| 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\` |


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