> For the complete documentation index, see [llms.txt](https://docs.kubchain.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.kubchain.com/quickstart/launching-a-token-on-kub/kap-token-interfaces/kap-721.md). # KAP-721 The following standard outlines a smart contract interface and logic for non-fungible tokens on KUB that supports an `adminTransfer` function designed to create transactions on behalf of NFT holders if they have been a victim of a fraudulent transaction. It is proposed by deriving the ERC-721 standard of Ethereum with additional functions related to `adminTransfer`. ## Token Interface ### IAdminProjectRouter #### isSuperAdmin Check whether `_addr` is the Super Admin role in `_project`. ```solidity function isSuperAdmin(address _addr, string calldata _project) external view returns (bool) ``` #### isAdmin Check whether `_addr` is the Admin role in `_project`. ```solidity function isAdmin(address _addr, string calldata _project) external view returns (bool) ``` ### IKYCBitkubChain #### kycsLevel Returns the KYC Level of `_addr`. ```solidity function kycsLevel(address _addr) external view returns (uint256) ``` ### IKAP165 #### supportsInterface Check whether the contract implements `interfaceID` and the `interfaceID` is not `0xffffffff`. ```solidity function supportsInterface(bytes4 interfaceId) external view returns (bool) ``` {% hint style="info" %} NOTE: Query if the contract implements an interface {% endhint %} ### IKAP721 #### balanceOf Returns the number of NFTs owned by the address `owner`, possibly zero. ```solidity function balanceOf(address owner) external view returns (uint256 balance) ``` {% hint style="info" %} NOTE: NFTs assigned to the zero address are considered invalid, and this function `throw` for queries about the zero address. {% endhint %} #### ownerOf Returns the address `owner` of the owner of the NFT `tokenID`. ```solidity function ownerOf(uint256 tokenId) external view returns (address owner); ``` {% hint style="info" %} NOTE: NFTs assigned to the zero address are considered invalid, and this function `throw` for queries about the zero address. {% endhint %} #### safeTransferFrom Transfers the ownership of NFT `tokenID` from address `from` to address `to`. * `throw` unless `msg.sender` is the current owner, an authorized operator, or the approved address for this NFT `tokenID`. * `throw` if `from` is not the current owner. * `throw` if `to` is the zero address. * `throw` if `tokenID` is not a valid NFT. When the transfer is complete, this function checks if `to` is a smart contract (code size > 0). If so, it calls `onKAP721Received` on `to` and `throw` if the return value is not `bytes4(keccak256("onKAP721Received(address,address,uint256,bytes)"))`. ```solidity function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external ``` #### transferFrom Transfers the ownership of NFT `tokenID` from address `from` to address `to`. * `throw` unless ‘msg.sender‘ is the current owner, an authorized operator, or the approved address for this NFT `tokenID`. * `throw` if `from` is not the current owner. * `throw` if `to` is the zero address. * `throw` if `tokenID` is not a valid NFT. ```solidity function transferFrom(address from, address to, uint256 tokenId) external ``` {% hint style="info" %} NOTE: The caller is responsible to confirm that `to` address is capable of receiving NFTs, or else they may be permanently lost. {% endhint %} #### adminTransfer Transfers NFT `tokenID` from address `from` to address `to`, and MUST fire the `Transfer` event. ```solidity function adminTransfer(address from, address to, uint256 tokenId) external ``` {% hint style="info" %} NOTE: This function can only be called by the Committee address required in the constructor. This function is designed to create transactions automatically on behalf of NFT holders if they have been a victim of a fraudulent transaction. This method works similarly to the `transferFrom` method. {% endhint %} #### internalTransfer Transfers NFT `tokenID` to address `to` internally from address `from`, and MUST fire the `Transfer` event. The function SHOULD `throw` if the message caller’s account balance does not have the specify NFT `tokenID`. NFTs can be transferred between internal addresses that have completed KYC for both the address `from` and the address `to` using the `internalTransfer` function. ```solidity function internalTransfer(address from, address to, uint256 tokenId) external returns (bool) ``` {% hint style="info" %} NOTE: This function can only be called by the Super Admin and the Transfer Router. {% endhint %} #### externalTransfer Transfers NFT `tokenID` to address `to` externally from address `from`, and MUST fire the `Transfer` event. The function SHOULD `throw` if the message caller’s account balance does not have the specified NFT `tokenID`. The function `externalTransfer` allows NFTs to be transferred between addresses that have only passed the sender’s KYC verification process. ```solidity function externalTransfer(address from, address to, uint256 tokenId) external returns (bool) ``` {% hint style="info" %} NOTE: This function can only be called by the Super Admin and the Transfer Router. {% endhint %} #### approve Change or reaffirm the approved address for an NFT `tokenID` to the address `to`. The zero address indicates there is no approved address. `throw` unless `msg.sender` is the current NFT owner, or an authorized operator of the current owner. ```solidity function approve(address to, uint256 tokenId) external ``` #### getApproved Returns the approved address `operator` for this NFT `tokenID`, or the zero address if there is none. `throw` if `tokenID` is not a valid NFT. ```solidity function getApproved(uint256 tokenId) external view returns (address operator) ``` #### setApprovalForAll Enable or disable approval for a third party `operator` to manage all of `msg.sender`'s assets. `approve` true if the `operator` is approved, false to revoke approval. Emits the `ApprovalForAll` event. The contract MUST allow multiple operators per owner. ```solidity function setApprovalForAll(address operator, bool approved) external ``` #### isApprovedForAll Check whether `operator` is an approved operator for `owner`. ```solidity function isApprovedForAll(address owner, address operator) external view returns (bool) ``` {% hint style="info" %} NOTE: Query if an address `operator` is an authorized operator for another address `owner`. {% endhint %} #### safeTransferFrom Transfers the ownership of NFT `tokenID` from address `from` to address `to`. This works identically to the other function with an extra data parameter, except this function sets data to “”. ```solidity function safeTransferFrom(address from, address to, uint256 tokenId) external ``` ### Events #### Transfer This event emits when ownership of any NFT `tokenID` changes by any mechanism, when NFTs are created (`from` == `0`), and when NFTs are destroyed (`to` == `0`). ```solidity event Transfer(address indexed from, address indexed to, uint256 indexed tokenId) ``` {% hint style="info" %} EXCEPTION: During contract creation, any number of NFTs may be created and assigned without emitting `Transfer`. At the time of any transfer, the approved address for that NFT (if any) is reset to none. {% endhint %} #### Approval This event emits when the `approved` address for an NFT `tokenID` is changed or reaffirmed. The zero address indicates there is no approved address. When a transfer event emits, this also indicates that the approved address for that NFT (if any) is reset to none. ```solidity event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId) ``` #### ApprovalForAll This event emits when `operator` is enabled or disabled for `owner`. The `operator` can manage all NFTs of the `owner`. ```solidity event ApprovalForAll(address indexed owner, address indexed operator, bool approved) ``` ### IKAP721V2 #### tokenOfOwnerByPage Returns the list of token identifier for the NFT from `page` to `limit` assigned to `owner`, (sort order not specified). * `throw` if `limit` is greater than or equals to `balanceOf(owner)` * `throw` if `page` is less than `0` * `throw` if `limit` is less than `0` * `throw` if `owner` is the zero address, representing invalid NFTs. ```solidity function tokenOfOwnerByPage(address owner, uint256 page, uint256 limit) external view returns (uint256[] memory) ``` #### tokenOfOwnerAll Returns the array of all token identifiers for the NFT assigned to `owner`, (sort order not specified). ```solidity function tokenOfOwnerAll(address owner) external view returns (uint256[] memory) ``` #### adminApprove Change or reaffirm the approved address for an NFT `tokenID` to the address `to`. The zero address indicates there is no approved address. This method works similarly to the `approve` method. `throw` unless `msg.sender` is the current NFT owner, or an authorized operator of the current owner. ```solidity function adminApprove(address to, uint256 tokenId) external ``` {% hint style="info" %} NOTE: This function can only be called by the Admin and Super Admin. This function is designed to create transactions automatically on behalf of token holders if they have been victims of a fraudulent transaction. {% endhint %} #### adminSetApprovalForAll Enable or disable approval for a third party `operator` to manage all of `msg.sender` assets. `approve` true if the `operator` is approved, false to revoke approval. This method works similarly to the `setApprovalForAll` method. Emits the `ApprovalForAll` event. The contract MUST allow multiple operators per owner. ```solidity function adminSetApprovalForAll(address owner, address operator, bool approved) external ``` {% hint style="info" %} NOTE: This function can only be called by the Admin and Super Admin. This function is designed to create transactions automatically on behalf of token holders if they have been victims of a fraudulent transaction. {% endhint %} ### IKAP721Metadata #### name A descriptive name for a collection of NFTs in this contract. ```solidity function name() external view returns (string memory) ``` #### symbol An abbreviated name for NFTs in this contract ```solidity function symbol() external view returns (string memory) ``` #### tokenURI A distinct Uniform Resource Identifier (URI) for a given asset. `throw` if `tokenID` is not a valid NFT. URIs are defined in RFC 3986. The URI may point to a JSON file that conforms to the “KAP721 Metadata JSON Schema”. ```solidity function tokenURI(uint256 tokenId) external view returns (string memory) ``` ### IKAP721Enumerable #### totalSupply Returns a count of valid NFTs tracked by this contract, where each one of them has an assigned and queryable owner not equal to the zero address. ```solidity function totalSupply() external view returns (uint256) ``` #### tokenOfOwnerByIndex Returns the token identifier for the `index` NFT assigned to `owner`, (sort order not specified). `throw` if `index` is greater than or equal to `balanceOf(owner)` or if `owner` is the zero address, representing invalid NFTs. ```solidity function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId) ``` #### tokenByIndex Returns the token identifier for the `index` NFT, (sort order not specified). `throw` if `index` is greater than or equal to `totalSupply()` ```solidity function tokenByIndex(uint256 index) external view returns (uint256) ``` ### IKAP721Receiver #### onKAP721Received The KAP721 smart contract calls this function on the recipient after a `Transfer`. This function MAY `throw` to revert and reject the transfer. Return of other than the magic value `bytes4(keccak256("onKAP721Received(address,address,uint256,bytes)"))` MUST result in the transaction being reverted. ```solidity function onKAP721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4) ``` {% hint style="info" %} NOTE: The contract address should always be the message sender. {% endhint %} --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## 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. 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