Non-fungible tokens (NFTs) are objects with an identifier whose uniqueness is enforced by a blockchain. Additionally, each NFT also has specific metadata, also defined on its host blockchain, the most important of which is its owner.
The unique identifier of a non-fungible token, known as Token ID, is only unique within the smart contract where it is defined, but not globally unique. For applications that refer to the NFT within a smart contract, a locally unique identifier is sufficient. However, other applications sometimes need to refer to NFTs globally. This document is an attempt to map local Token IDs to more global identifier through the definition of a new URN namespace for NFTs.
The proposed namespace is urn:nft. The syntax is the following:
urn:nft:<nft_method>:<method_specific_identifier>
The <nft_method> component is the unique identifier for an NFT algorithm. Appendix A contains a registry with known NFT methods.
Each NFT method shall be defined within its own specification, and must detail how the <method_specific_identifier> is used to point to a specific NFT created using that method.
This URN namespace is experimental and hasn't yet gone through the steps of IANA registration.
This section lists known NFT methods, although it could be maintained as a separate document in the future.
| NFT Method | Description | Specification |
|---|---|---|
erc721 |
ERC-721 NFTs (based on Ethereum) | urn:nfc:erc721 specification |
Please file an issue if you would like to reference another urn:nft:<method>.