README.md

CIP	Title	Authors	Comments-URI	Status	Type	Created
To be confirmed?	721 Metatdatum extension property	Jack ([9000] pool, https://forum.cardano.org/u/jack7e/, @ada9000_ twitter)	cardano-foundation#249	Draft	Informational	2022-09-28

Abstract

This standard proposes a method to define optional extensions the 721 metadatum standard. Allowing users to know what to expect in the metadata.

Motivation

• Cardano NFT Metadata parsing is becoming complex due to optional metadata json tags.
• If Cardano NFT's want to develop we need to define what's inside the metadata to avoid conflicts with custom optional tags and tags defined in new CIPs.

Specification

• The ext tag is added within the "721" metadatum tag
• The ext tag should be lowercase. When parsing nft metadata the developer will use a to lowercase function on all elements in the ext array

{
   "721":{
      "ext": <array>
      "<policy_id>":{
         "<asset_name>": {
            "name": <string>,
            "image": <uri | array>
         }
      }
   }
}

Example usage

The theoretical cipX in this example defines a script tag that must be present. To implement this CIP in our 721 metadatum JSON we simply add CIPX to the "ext" array.

{
   "721":{
      "ext": ["cipX"]
      "<policy_id>":{
         "script":"<script_policy_id>"
         "<asset_name>": {
            "name": <string>,
            "image": <uri | array>
         }
      }
   }
}

Where cipX defines some property for the JSON. In this particular example cipX is a fictional CIP that requires the nft to contain a "script" tag with a "<script_policy_id>".