# Overview

[ERC-721](https://eips.ethereum.org/EIPS/eip-721) compliant contracts MAY implement this EIP to provide standard methods of locking and unlocking the token at its current owner address.

Token owner MAY `lock` the token and assign `locker` to some `address` using `lock(uint256 tokenId, address _locker)` function, this MUST set `locker` to `_locker`. Token owner or approved MAY `lock` the token using `lock(uint256 tokenId)` function, this MUST set `locker` to `msg.sender`. Token MAY be `unlocked` by `locker` using `unlock` function. `unlock` function MUST delete `locker` mapping and default to `address(0)`.

If the token is `locked`, the `lockerOf` function MUST return an address that is `locker` and can `unlock` the token. For tokens that are not `locked`, the `lockerOf` function MUST return `address(0)`.

`lock` function MUST revert if token is not already locked. `unlock` function MUST revert if token is not locked. ERC-721 `approve` function MUST revert if token is locked. ERC-721 `_tansfer` function MUST revert if token is locked. ERC-721 `_transfer` function MUST pass if token is locked and `msg.sender` is `approved` and `locker` both. After ERC-721 `_transfer`, values of `locker` and `approved` MUST be purged.

Token MAY be transferred and `locked`, and OPTIONAL setup `approval` to `locker` using `transferAndLock` function. This is RECOMMENDED for use-cases where Token transfer and subsequent revocation is REQUIRED.

#### INTERFACE

```
// SPDX-License-Identifier: CC0-1.0

pragma solidity >=0.7.0 <0.9.0;

/// @title Lockable Extension for ERC721
/// @dev Interface for the Lockable extension
/// @author StreamNFT 

interface IERC7066{

    /**
     * @dev Emitted when tokenId is locked
     */
    event Lock (uint256 indexed tokenId, address _locker);

    /**
     * @dev Emitted when tokenId is unlocked
     */
    event Unlock (uint256 indexed tokenId);

    /**
     * @dev Lock the tokenId if msg.sender is owner or approved and set locker to msg.sender
     */
    function lock(uint256 tokenId) external;

    /**
     * @dev Lock the tokenId if msg.sender is owner and set locker to _locker
     */
    function lock(uint256 tokenId, address _locker) external;

    /**
     * @dev Unlocks the tokenId if msg.sender is locker
     */
    function unlock(uint256 tokenId) external;

    /**
     * @dev Tranfer and lock the token if the msg.sender is owner or approved. 
     *      Lock the token and set locker to caller
     *      Optionally approve caller if bool setApprove flag is true
     */
    function transferAndLock(uint256 tokenId, address from, address to, bool setApprove) external;

    /**
     * @dev Returns the wallet, that is stated as unlocking wallet for the tokenId.
     *      If address(0) returned, that means token is not locked. Any other result means token is locked.
     */
    function lockerOf(uint256 tokenId) external view returns (address);
}
```


---

# 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://docs.streamnft.tech/streamnft-protocol/erc-7066/overview.md?ask=<question>
```

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.