LSP4 - Digital Asset Metadata

Standard Document

LSP4 - Digital Asset Metadata

Introduction

The existing tokens and NFTs standards offer limited functionalities to attach information to the contracts themselves. As an example, the ERC20 and ERC721 standards only define a name(), symbol(), and tokenURI() functions. This makes it difficult to add information more specific to the asset (e.g., an icon, the asset creator(s) , the utility or motive of the token, the community behind it, etc...). Such information is crucial to make each token or NFT descriptive and customised.

LSP4-DigitalAsset-Metadata solves this problem by defining a set of data keys to describe a Digital Asset using ERC725Y as a backbone. ERC725Y enables smart contracts to have very flexible and extensible storage. With ERC725Y, any information or metadata can be attached to the token or NFT.

Types of Digital Assets

By mixing contract standards (LSP7/8), token types (Token, NFT, Collection) and metadata, you can create a wide array of Digital Assets.

With LSP7 Digital Asset (Token)

Contract type	LSP4TokenType	Decimals	LSP4Metadata	Description
LSP7	0 (Token)	>=0	Represents the token information.	A generic token, where the LSP4Metadata represents the token information.
LSP7	1 (NFT)	0	Represents the information of a single NFT, that has multiple ownable amounts or IDs.	A single type of NFT with custom metadata and which has multiple ownable amounts or IDs.
LSP7	2 (Collection)	-	-	Not compatible

With LSP8 Identifiable Digital Asset (NFT)

Contract type	LSP4TokenType	LSP4Metadata for Contract	LSP8TokenIdFormat	LSP4Metadata for each TokenId	Description
LSP8	0 (Token)	-	-	-	Not compatible
LSP8	1 (NFT)	Represents the information of a single NFT, that has multiple ownable amounts or IDs.	COULD be set for each individual token ID.	COULD be set for each individual token ID.	Each individual token ID COULD have its own custom metadata specific for the token ID, but MUST NOT be a different NFT, just different metadata per item in the NFT. See LSP8 for details.
LSP8	2 (Collection)	Represents the information of the collection.	MUST be set for each individual token ID.	MUST be set for each individual token ID.	Each individual token ID represents its own NFT, LSP4Metadata and LSP8TokenIdFormat must be set for each of them in case the individual token IDs are LSP8. See LSP8 for details.

ERC725Y Data Keys

Recommendation

Make sure to understand the ERC725Y Generic Key/Value Store and LSP2 - ERC725YJSONSchema Standards before going through the ERC725Y Data Keys.

SupportedStandards:LSP4DigitalAsset

{
  "name": "SupportedStandards:LSP4DigitalAsset",
  "key": "0xeafec4d89fa9619884b60000a4d96624a38f7ac2d8d9a604ecf07c12c77e480c",
  "keyType": "Mapping",
  "valueType": "bytes4",
  "valueContent": "0xa4d96624"
}

This key is used to know if the contract represents a Digital Asset.

LSP4TokenName

{
  "name": "LSP4TokenName",
  "key": "0xdeba1e292f8ba88238e10ab3c7f88bd4be4fac56cad5194b6ecceaf653468af1",
  "keyType": "Singleton",
  "valueType": "string",
  "valueContent": "String"
}

The value attached to this data key represents the name of the digital asset.

LSP4TokenSymbol

{
  "name": "LSP4TokenSymbol",
  "key": "0x2f0a68ab07768e01943a599e73362a0e17a63a72e94dd2e384d2c1d4db932756",
  "keyType": "Singleton",
  "valueType": "string",
  "valueContent": "String"
}

The value attached to this data key represents the symbol of the digital asset.

LSP4TokenType

References

LSP4 defines 3 default token types (see table above). However, these are not restrictive. Applications and protocols can define new custom token types starting from 3.

{
  "name": "LSP4TokenType",
  "key": "0xe0261fa95db2eb3b5439bd033cda66d56b96f92f243a8228fd87550ed7bdfdb3",
  "keyType": "Singleton",
  "valueType": "uint256",
  "valueContent": "Number"
}

The value attached to this data key repesents the type of token of the digital asset. The defaults values are:

• 0 (Token)
• 1 (NFT)
• 2 (Collection)

tip

👉 Please refer to the Types of Digital Assets table to see how you can use it to create your assets.

LSP4Metadata

{
  "name": "LSP4Metadata",
  "key": "0x9afb95cacc9f95858ec44aa8c3b685511002e30ae54415823f406128b85b238e",
  "keyType": "Singleton",
  "valueType": "bytes",
  "valueContent": "VerifiableURI"
}

The value attached to this data key is a VerifiableURI. It represents a reference to a JSON file describing the Digital Asset. The file can be stored on centralized or decentralized storage.

LSP4Creators

This data key refers to the address(es) of the creator(s) of the digital asset. It can help to check the asset authenticity when combined with LSP12-IssuedAssets.

{
  "name": "LSP4Creators[]",
  "key": "0x114bd03b3a46d48759680d81ebb2b414fda7d030a7105a851867accf1c2352e7",
  "keyType": "Array",
  "valueType": "address",
  "valueContent": "Address"
}

{
  "name": "LSP4CreatorsMap:<address>",
  "key": "0x6de85eaf5d982b4e5da00000<address>",
  "keyType": "Mapping",
  "valueType": "(bytes4,uint128)",
  "valueContent": "(Bytes4,Number)"
}

References

• LUKSO Standards Proposals: LSP4 - Digital Asset Metadata (Standard Specification, GitHub)