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.

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 below). 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.

Value	Type	Description
0	Token	Only valid for LSP7, meaning its a generic token, where the LSP4Metadata represents the token information.
1	NFT	If the contract is LSP7 or LSP8, then the LSP4Metadata represents the information of a single NFT, that has multiple ownable amounts or IDs. If its an LSP8 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. Those COULD be set using LSP8TokenIdType and LSP8MetadataTokenURI. See LSP8 for details. If its an LSP7 contract, the decimals function MUST return 0.
2	Collection	Only valid for LSP8. The LSP4Metadata represents the information of a the collection, and each individual token ID represents its own NFT and MUST have its own metadata set using LSP8TokenIdType and LSP8MetadataTokenURI. See LSP8 for details.

LSP4Metadata

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

The value attached to this data key is a JSONURL. 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)