# IERC20Permit *Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in ]. Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't need to send a transaction, and thus is not required to hold Ether at all.* ## Methods ### DOMAIN\_SEPARATOR ```solidity function DOMAIN_SEPARATOR() external view returns (bytes32) ``` *Returns the domain separator used in the encoding of the signature for `permit`, as defined by {EIP712}.* #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | bytes32 | undefined | ### nonces ```solidity function nonces(address owner) external view returns (uint256) ``` *Returns the current nonce for `owner`. This value must be included whenever a signature is generated for {permit}. Every successful call to {permit} increases `owner`'s nonce by one. This prevents a signature from being used multiple times.* #### Parameters | Name | Type | Description | | ----- | ------- | ----------- | | owner | address | undefined | #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | uint256 | undefined | ### permit ```solidity function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external nonpayable ``` *Sets `value` as the allowance of `spender` over `owner`'s tokens, given `owner`'s signed approval. IMPORTANT: The same issues {IERC20-approve} has related to transaction ordering also apply here. Emits an {Approval} event. Requirements: - `spender` cannot be the zero address. - `deadline` must be a timestamp in the future. - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner` over the EIP712-formatted function arguments. - the signature must use `owner`'s current nonce (see {nonces}). For more information on the signature format, see the EIP section].* #### Parameters | Name | Type | Description | | -------- | ------- | ----------- | | owner | address | undefined | | spender | address | undefined | | value | uint256 | undefined | | deadline | uint256 | undefined | | v | uint8 | undefined | | r | bytes32 | undefined | | s | bytes32 | undefined | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://contracts.synapseprotocol.com/elin/contracts/drafts/ierc20permit.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.