Metadata formatting

Specification of the expected metadata formatting

RMRK standards expect the metadata to be structured according to ERC-721 specification. Having multiple kinds of resources (assets, parts, and collections) means that there is some variation in the metadata of each:
Metadata examples
Examples of metadata structures for all of the resources.
Collection metadata
Here is an example of the metadata of the collection:
{
  "name": "Collection Name",
  "description": "The description of the collection",
  "mediaUri": "ipfs://mediaOfTheCollection",
  "externalUri": "https://uriToTheProjectWebsite",
  "license": "License name",
  "licenseUri": "https://uriToTheLicense",
  "tags": ["tags", "used", "to", "help", "marketplaces", "categorize", "the", "asset", "or", "token"],
}
Asset metadata
Here is an example of the metadata of an ERC-5773 compliant asset:
{
  "name": "Asset Name",
  "description": "The description of the token or asset",
  "mediaUri": "ipfs://mediaOfTheAssetOrToken",
  "thumbnailUri": "ipfs://thumbnailOfTheAssetOrToken",
  "externalUri": "https://uriToTheProjectWebsite",
  "license": "License name",
  "licenseUri": "https://uriToTheLicense",
  "tags": ["tags", "used", "to", "help", "marketplaces", "categorize", "the", "asset", "or", "token"],
  "preferThumb": false, // A boolean flag indicating to UIs to prefer thumbnailUri instead of mediaUri wherever applicable
  "attributes": [
    {
      "label": "rarity",
      "type": "string",
      "value": "epic",
      // For backward compatibility
      "trait_type": "rarity"
    },
    {
      "label": "color",
      "type": "string",
      "value": "red",
      // For backward compatibility
      "trait_type": "color"
    },
    {
      "label": "height",
      "type": "float",
      "value": 192.4,
      // For backward compatibility
      "trait_type": "height",
      "display_type": "number"
    }
  ]
}
Catalog part metadata
Here is an example of the metadata of an ERC-6220 compliant part:
{
  "name": "Kanaria headwear slot",
  "description": "This is a Kanaria headwear slot, you can equip nested NFTs with a compatible asset in it.",
  "mediaUri": "ipfs://ipfs/XXXX/headwear_slot_fallback.svg",
  "attributes": [
    {
      "label": "rarity",
      "type": "string",
      "value": "rare",
      // For Opensea backward compatibility
      "trait_type": "rarity"
    }
  ]
}
 Metadata schema definition
The top-level metadata types supported are:
Base metadata field
Type
Description
Required
name
string
Resource name.
✅
description
string
General notes, abstracts, or summaries about content.
❌
license
string
The name of the license appended to the resource.
❌
licenseUri
string
The URI linking to the license body.
❌
mediaUri
string
The URI to the main media file of the resource.
❌
thumbnailUri
string
The URI to be used in wallets and client applications, where a scaled-down image is needed in order to present the resource to the end user.
❌
tags
array
An array of string values used to help marketplaces categorize the resource.
❌
preferThumb
bool
The flag used to signal to UIs to prefer the thumbnailUri instead of mediaUri where applicable.
❌
attributes
array
An array of custom attributes specific to the resource it represents.
❌
Supported attribute types
Attributes can be completely custom to cater to the resource they are describing. The supported attribute types are:
number
float
integer
string
date
percentage
boolean
To observe how the attributes array is structured, you can refer to the Asset metadata example above.

Base metadata field	Type	Description	Required
`name`	string	Resource name.	✅
`description`	string	General notes, abstracts, or summaries about content.	❌
`license`	string	The name of the license appended to the resource.	❌
`licenseUri`	string	The URI linking to the license body.	❌
`mediaUri`	string	The URI to the main media file of the resource.	❌
`thumbnailUri`	string	The URI to be used in wallets and client applications, where a scaled-down image is needed in order to present the resource to the end user.	❌
`tags`	array	An array of string values used to help marketplaces categorize the resource.	❌
`preferThumb`	bool	The flag used to signal to UIs to prefer the `thumbnailUri` instead of `mediaUri` where applicable.	❌
`attributes`	array	An array of custom attributes specific to the resource it represents.	❌

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