Referable Non-Fungible Tokens
ERC 721 defines the Ethereum standard API to mint NFTs (Non-Fungible Tokens). While an NFT minted with ERC 721 represents something in the world standalone (e.g., an artwork, a copyright, or equipment in the metaverse), it does not reflect the reality/fact that many things in the world are related to or depend on each other, such as: (a) a film is based on a novel; (b) a song is from composing lyrics based on a piece of music, vice versa. Based on this observation, we proposed an extension of ERC 721, called Referable NFTs, by enabling a new NFT to refer 1-to-n the existing NFTs, according to their natural relationship. The proposal was submitted to the Ethereum Foundation in August 2022 and has been finalised in June 2024 and become an Ethereum standard now, i.e. ERC-5521. For details, please visit: https://eips.ethereum.org/EIPS/eip-5521

We believe a lot of real-world applications can leverage ERC-5521 to define/bind the things and their relationships. Like other ERC standards, ERC-5521’s application space would be only limited by our imagination.