The Minimalistic Transferable interface for Non-Fungible Tokens standard extends ERC-721 by introducing the ability to identify whether an NFT can be transferred or not.
This proposal introduces the ability to prevent a token from being transferred from their owner, making them bound to the externally owned account, abstracted account, smart contract or token that owns it.
This is meant to be used as an extension and supports limiting transferability based on the sending and receiving address.
Check implementations here
We published an Ethereum Improvement Proposal detailing the specification of the Soulbound RMRK extension. If you are interested, you can access it here (opens in a new tab).