I learnt somewhere today that an erc721 token doesn't have to belong to an account, it could belong to another erc721!

How can this be implemented? where can I read more of this?


2 Answers 2


The ERC-721 standard only describes the smart contract interface for a non-fungible token on the Ethereum blockchain. It provides basic functionality to track and transfer NFTs. A token, in this case, can only belong to a physical address - to an account - which can be a user's wallet or another smart contract.

Probably the best you can do is to extend your smart contract and make it chainable. This, however, has nothing to do with the ERC-721 spec.

UPDATE (20.04.2018):

I think your use case is targeting Composable NFT (ERC-998) or Delegated Non-Fungible Tokens (ERC-994).

  • Thanks got it!! I think i will basically create a new ERC721 that combines both 721 token attribute or something and interpret that as one belongs to the other
    – Zhen Liu
    Apr 19, 2018 at 16:16

The ERC-721 draft standard requires that each token have one (and only one) owner. The owner of each token is identified by their address, and since an individual ERC-721 token does not have its own address, no this isn't possible.

However, there is no requirement that the owner be a wallet address, a token can belong to another contract. So the owner of a token can be another ERC-721 contract (or even the same contract), but not another token.

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