Non-transferable NFTs

Non-transferable NFTs, popularized by Vitalik Buterin as soulbound, are NFTs that are useful for reputation tracking: they get added to addresses but are non-transferable, so they cannot be sold and permanently assign some modifier to a given address.

In RMRK this is an especially interesting concept as NFTs can be non-transferable inside another transferable NFT. Thus, an NFT like a Kanaria can have non-transferable gems inside it that give it long lasting benefits and bonuses, but cannot be removed.

This can be further utilized when dealing with in-game avatars and skill systems. A skill can be learned and "installed" into an avatar's brain, but cannot be removed.

In addition to a simple on/off flag, the Kusama implementation (see below) supports temporary transferability and temporary non-transferability which allows a minter to specify that an NFT should be movable only after a certain number of blocks, or not before a certain number of blocks.

Implementations

The implementations below lead directly to code. For examples of how to utilize them to mint your own NFTs, please refer to the sidebar section for each implementation subtype.

• Kusama
• [EVM](in development)
• [Pallets](in development)