TreeTrunk, a startup, has developed a variation of the NFT-specific protocol known as ERC-721. TreeTrunk has modified the protocol in such a way as to make it easy for an artist to mint a master NFT of her work, then sell derivatives of that NFT to fans—who can in turn sell it to other fans.
Source: Ethereum NFT Protocol TreeTrunk Promises New Royalty Options for Artists – Decrypt