Standardising the metadata layer with ERC-6551B

NIP Submission Template

Author’s Information

I am Product Morty, a product lead with experiences working in startup, incubators and consultancies with a specialised focus on getting new initiatives off the ground. I can be contacted
via discord productmorty or
via Twitter @productmorty
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Simple Summary

This NIP proposes the creation of a standardised metadata layer for NFTs, building on the foundations of ERC6551: Token Bound Accounts.


The primary innovation of this NIP is the introduction of a standardized metadata layer to the existing ERC6551, effectively evolving static NFTs into dynamic ones. This proposed standard not only amplifies the usability and versatility of NFTs but also heightens the potential for cross-platform and cross-application interoperability. By converting static NFTs into dynamic ones, we are enhancing the NFT ecosystem and providing a more interactive and immersive user experience.


The motivation for proposing this NIP is to overcome the current limitations of NFTs in terms of customization and versatility. As NFTs become increasingly integrated into the digital world, there is a need to allow for more personalisation, interoperability and dynamic features. By integrating a standardized metadata layer with dynamic attributes, this NIP intends to push the boundaries of what NFTs are capable of, thereby contributing to the development and evolution of the NFT ecosystem. The proposal also aims to attract more developers and users to the NFT space by providing a more enhanced and immersive experience.

As part of the initiative of Mint to create a new ecosystem of innovative NFTs, I believe they need to create the necessary mechanisms to get the best and brightest devs to choose their blockchain as the launchpad. (why choose Mint (and consequently OP) and not ARB / SOL / ETH / POLY etc)

One of the main ways to do this is to provide unique or established guardrails that allow the dev the best experience in bringing their idea to life. Part of that is creating the right backend for the middleware / frontend to connect to. With the right API configurations in place, it will be a lot easier to modularise the core capabilities to create and maintain a RPG game which has a burn mechanism centred around weapon utilisation.


The rationale for this NIP is based on the understanding that the current NFT standards, while revolutionary, are somewhat limited in their applicability. Given that NFTs are non-fungible, their value lies in their uniqueness. However, this uniqueness is currently static and unchanging. By adding a standardized metadata layer that can change based on the contents of an NFT’s wallet, we can create a dynamic system where NFTs are not just unique, but also adaptable and customizable to individual user’s needs. This dramatically increases the range of applications and uses for NFTs.

One of the key applications of this proposal is in the creation of personalized digital identities. By splitting an NFT’s attributes into a standardized metadata layer, users will have the ability to customize their digital identities in a modular way. This means that a user could swap out specific attributes of an NFT, such as clothing or accessories, allowing for a higher degree of personalization and representation.

Creating a meta-data layer around clothing for digital identities:

Currently PFPs are provided as Image and metadata but the metadata serves nothing except perceived rarity (and in turn value) of the NFT. With the ERC6551B standard, the NFT would be split into the meta-data attributes, for simplicity sake we will say that NFT-A has the following meta-data enabled
- a hat, shirt, outerwear, accessory hand, accessory neck.

With this new proposed standard, NFT-A could now have its hat swapped out with any other NFT that has the meta-data of a Hat. This provides collections the ability to sustain revenue post mint. (imagine BAYC creates a hat collection) This analogy can be pushed further and say that any NFT could wear any other NFT that has that standard applied. (Pudgy wearing a BAYC hat)

For PFPs to truly be a representation of a digital identity, someone should be able to change their appearance. This enables people to do this on a modular level, as opposed to changing NFTs as their profile picture.

The gaming industry is another sector where this proposal can have profound implications.

By allowing NFTs to hold a ‘backpack’ of craftable assets such as weapons or consumables, the gaming experience can be significantly enhanced. This also opens up new possibilities for game developers, who can now create more immersive and interactive gaming experiences.

This example can be extended extremely well into craftable assets for gaming:

  • NFT assets (such as characters) can now have a backpack of consumables, weapons and accessories which can augment the characteristics of the base NFT.

  • Projects with this meta-layer enabled, (such as left hand weapon, right hand weapon, armour, helmet) has better capability of handling depreciation of utility per asset. Going back to the previous generation of NFTs in gaming, attributes (and weapons) were part of the same meta-layer, which made it a challenge to associate any live data around the accessory itself.

  • To bring this idea to life, imagine a warrior NFT that has the following attributes:
    -strength - 10
    - defense - 8
    - dexterity - 5
    - intelligence - 5
    and also had
    - left hand weapon - sword (+2 strength)
    - right hand weapon - shield (+5 defense)

  • With the new meta-layer, you could also introduce new attributes per accessory such as:

  • wear (new - aged), luck (chance for critical effect), upgrades (an attribute to associate power ups to the accessory)

  • All of which would improve the level of gameplay for any game. In the same way that hats could be swapped on a PFP, a character would be able to buy new weapons to equip or store for future use.

But the following example showcases how it could also be used for dramatically different purposes and illustrates the extensiveness of the idea:

  • With the ERC6551B you could have have a much better experience for card games as each based NFT could signify a booster pack (5 NFTs which have been unrevealed) or a deck (30 cards which you can utilise for play or tournament). Part of this is to bring some of the capabilities which had to be done offchain - onchain. This could bring a whole new level of analytics for card games by understanding what top ranked players use in their decks.

Moreover, the proposed standard also has potential applications in real-world business scenarios.

For instance, businesses could use this standard to offer personalized rewards and discounts to their customers by airdropping tokens into the users’ NFT wallets. This not only leads to increased customer engagement but also provides businesses with a new way to monetize their services.

  • Imagine starbucks odessy (the membership program) started to utilise ERC-6551B for their base NFT.

  • That would mean each membership pass has its own wallet (backpack). This allows starbucks to potentially airdrop a POAP that shows that this membership has bought 1 vente latte. This is then extended when starbucks chooses to airdrop discounts, free drinks or coupons for merch directly into the membership pass (potentially as a soul bound token) and not the wallet associated with the membership pass.

  • This creates value for the inherit pass and as a consequence the holder of the pass. If however that person wanted to sell the pass, their pass would be worth significantly more because it has a whole bunch of redeemables he didn’t use.

  • This is a major step towards SocialFi that provides reasons for mass onboarding and could create a huge reason for major corporates to test out web 3.0 again. I believe it is imperative to create net new value propositions that isn’t possible in their current ecosystem in order to convince web 2 organisations to take the plunge into this new world (again)

A critical application of this proposal can be seen in the field of education and information dissemination services,

  • Imagine a subscription model where each subscriber gets a membership pass (ERC-6551B standard NFT) that has its own ‘wallet’ or ‘backpack’. Every month, the publisher / content creator airdrops a token into the pass that can be redeemed to access and read a premium article or publication. This system changes the way we perceive value in digital subscriptions.

  • The current subscription model often encourages binge-reading to extract the most value from the subscription, which often leads to information overload and a diminished value in the content. But with this new model, time and information curation becomes a key feature. Users can choose to spend their tokens on the articles that they find most valuable, incentivizing a more mindful and selective approach to consuming content.

  • Moreover, these tokens can also be traded or sold, adding a new layer of utility to the subscription. For example, if a user finds they have excess tokens or an article they are not interested in, they could potentially sell or trade the token to someone else who does have an interest. This creates a secondary market, further enhancing the value proposition of the subscription.

  • Furthermore, for the publisher, this system also offers new ways to engage with their audience. They could offer different tiers of articles requiring different numbers of tokens, or even special editions or early access content that can only be accessed with a specific type of token. This also opens up new monetization opportunities, as publishers could sell additional tokens or special tokens directly to their audience.

  • In essence, the integration of the ERC-6551B standard to digital subscriptions can revolutionize the way we engage with educational and informative content, fostering a more mindful, rewarding, and interactive experience for both consumers and publishers. Implementing this standard would require careful planning and execution, but the benefits to the information industry and its consumers could be immense.

The implementation of this standard will require a significant effort, considering that it represents a new paradigm for NFTs. It introduces a new level of complexity to the NFT space and will require a strong technical foundation to ensure its successful implementation. The implementation process will need to adhere to the principles of transparency, security and user-friendliness to ensure its acceptance and adoption by the community.

Specification (Non-Mandatory)

Mint Testnet could try and implement this and start creating the core data attributes for the different verticals and test it with a cohort of NFT projects. The idea is to launch into mainnet with a solidified view of the different metadata layer and mechanisms on its potential towards further inteorporability. As an example, you could launch a few fashion brands and some PFPs as a consortium to help support the ERC-6551B metadata layer for clothing and provide a marketplace for hats, clothing and accessories for users to buy and glamour out their new NFTs.

The other major consideration is on frontend side and creating the ability to visually manifest these changes. Obviously we have seen in the previous era that PFPs can come in all kinds of different shapes and sizes. It is important to create the capabilitities to morph not only the backend data but also to create the mechanisms to allow it to be visually showcased. I think a good starting point is to have key mesh points identified for all PFPs (base NFT) and then for the accessories (NFTs utilising ERC-6551B) to be bound in relation to mesh points dictated by their metadata property. I think alot of the meshing could be done relatively easily by gen-AI and would be a huge step towards inteorporablility.

Open-source commitment
“I commits to open-sourcing the NIP and grants permission for developers within the Mint blockchain ecosystem to build protocols and applications based on this NIP.”

1 Like

Hey there. I think most if not all of what you are suggesting is already possible with a combination of existing ERCs.

ERC-7409 allows you to do dynamic cross collection nesting, so NFTs can own others. Then with ERC-5773 you can have each NFT dynamically have multiple assets so you display the right one depending on the context. Finally with ERC-6220 you can do equipping. So you have for instance a character NFT which defines some slots to equip others (left hand, right hand, armor, helmet…). You send the items to the character and those are also NFTs which have multiple assets, including the ones to render correctly when equipped into the parent. It’s all dynamic and all info lives in the blockchain. All this are final standards, unlike 6551 which is still in review.

As for attributes there is this draft: ERC-7508 for a common good attributes repository living on the same address in every blockchain.

All these have been battle tested for over a year now, and there is an EVM package with minimal and ready to use implementations for all the mentioned ERCS, docs with use cases, tutorials and detailed API even a wizard, OpenZeppelin style.

Hope it helps!