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arc: 69 title: Community Algorand Standard Asset Parameters Conventions for Digital Media Tokens status: Living Standard

Community Algorand Standard Asset Parameters Conventions for Digital Media Tokens

Summary

We introduce community conventions for the parameters of Algorand Standard Assets (ASAs) containing digital media.

Abstract

The goal of these conventions is to make it simpler to display the properties of a given ASA. This ARC differs from ARC3 by focusing on optimization for fetching of digital media, as well as the use of onchain metadata. Furthermore, since asset configuration transactions are used to store the metadata, this ARC can be applied to existing ASAs.

While mutability helps with backwards compatibility and other use cases, like leveling up an RPG character, some use cases call for immutability. In these cases, the ASA manager MAY remove the manager address, after which point the Algorand network won't allow anyone to send asset configuration transactions for the ASA. This effectively makes the latest valid ARC-69 metadata immutable.

Specification

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119.

An ARC-69 ASA has an associated JSON Metadata file, formatted as specified below, that is stored on-chain in the most recent asset configuration transaction.

ASA Parameters Conventions

The ASA parameters should follow the following conventions:

• Unit Name (un): no restriction.
• Asset Name (an): no restriction.
• Asset URL (au): a URI pointing to digital media file. This URI:
  • SHOULD be persistent.
  • SHOULD link to a file small enough to fetch quickly in a gallery view.
  • MUST follow RFC-3986 and MUST NOT contain any whitespace character.
  • SHOULD specify media type with # fragment identifier at end of URL. This format MUST follow: #i for images, #v for videos, #a for audio, #p for PDF, or #h for HTML/interactive digital media. If unspecified, assume Image.
  • SHOULD use one of the following URI schemes (for compatibility and security): https and ipfs:
    • When the file is stored on IPFS, the ipfs://... URI SHOULD be used. IPFS Gateway URI (such as https://ipfs.io/ipfs/...) SHOULD NOT be used.
  • SHOULD NOT use the following URI scheme: http (due to security concerns).
• Asset Metadata Hash (am): the SHA-256 digest of the full resolution media file as a 32-byte string (as defined in NIST FIPS 180-4)
  • OPTIONAL
• Freeze Address (f):
  • SHOULD be empty, unless needed for royalties or other use cases
• Clawback Address (c):
  • SHOULD be empty, unless needed for royalties or other use cases

There are no requirements regarding the manager account of the ASA, or the reserve account. However, if immutability is required the manager address MUST be removed.

JSON Metadata File Schema

{
    "title": "Token Metadata",
    "type": "object",
    "properties": {
        "standard": {
            "type": "string",
            "value": "arc69",
            "description": "(Required) Describes the standard used."
        },
        "description": {
            "type": "string",
            "description": "Describes the asset to which this token represents."
        },
        "external_url": {
            "type": "string",
            "description": "A URI pointing to an external website. Borrowed from Open Sea's metadata format (https://docs.opensea.io/docs/metadata-standards)."
        },
        "media_url": {
            "type": "string",
            "description": "A URI pointing to a high resolution version of the asset's media."
        },
        "properties": {
            "type": "object", 
            "description": "Properties following the EIP-1155 'simple properties' format. (https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1155.md#erc-1155-metadata-uri-json-schema)"
        },
        "mime_type": {
            "type": "string",
            "description": "Describes the MIME type of the ASA's URL (`au` field)."
        },
        "attributes": {
            "type": "array",
            "description": "(Deprecated. New NFTs should define attributes with the simple `properties` object. Marketplaces should support both the `properties` object and the `attributes` array). The `attributes` array follows Open Sea's format: https://docs.opensea.io/docs/metadata-standards#attributes"
        }
    }
}

The standard field is REQUIRED and MUST equal "arc69". All other fields are OPTIONAL. If provided, the other fields MUST match the description in the JSON schema.

The URI field (external_url) is defined similarly to the Asset URL parameter au. However, contrary to the Asset URL, the external_url does not need to link to the digital media file.

MIME Type

In addition to specifying a data type in the ASA's URL (au field) with a URI fragment (ex: #v for video), the JSON Metadata schema also allows indication of the URL's MIME type (ex: video/mp4) via the mime_type field.

Examples

Basic Example

An example of an ARC-69 JSON Metadata file for a song follows. The properties array proposes some SUGGESTED formatting for token-specific display properties and metadata.

{
  "standard": "arc69",
  "description": "arc69 theme song",
  "external_url": "https://www.youtube.com/watch?v=dQw4w9WgXcQ",
  "mime_type": "video/mp4",
  "properties": {
    "Bass":"Groovy", 
    "Vibes":"Funky", 
    "Overall":"Good stuff"
  }
}

An example of possible ASA parameters would be:

• Asset Name: ARC69 theme song for example.
• Unit Name: 69TS for example.
• Asset URL: ipfs://QmWS1VAdMD353A6SDk9wNyvkT14kyCiZrNDYAad4w1tKqT#v
• Metadata Hash: the 32 bytes of the SHA-256 digest of the high resolution media file.
• Total Number of Units: 1
• Number of Digits after the Decimal Point: 0

Mutability

Rendering

Clients SHOULD render an ASA's latest ARC69 metadata. Clients MAY render an ASA's previous ARC69 metadata for changelogs or other historical features.

Updating ARC69 metadata

Managers MAY update an ASA's ARC69 metadata. To do so, they MUST send a new acfg transaction with the entire metadata represented as JSON in the transaction's note field.

Making ARC69 metadata immutable

Managers MAY make an ASA's ARC69 immutable. To do so, they MUST remove the ASA's manager address with an acfg transaction.

ARC69 attribute deprecation

The initial version of ARC69 followed the Open Sea attributes format. As illustrated below:

"attributes": {
"type": "array",
"description": "Attributes following Open Sea's attributes format (https://docs.opensea.io/docs/metadata-standards#attributes)."
}

This format is now deprecated. New NFTs SHOULD use the simple properties format, since it significantly reduces the metadata size.

To be fully compliant with the ARC69 standard, both the properties object and the attributes array SHOULD be supported.

Rationale

These conventions take inspiration from Open Sea's metadata standards and EIP-1155 to facilitate interoperobility.

The main differences are highlighted below:

• Asset Name, Unit Name, and URL are specified in the ASA parameters. This allows applications to efficienty display meaningful information, even if they aren't aware of ARC-69 metadata.
• MIME types help clients more effectively fetch and render media.
• All asset metadata is stored onchain.
• Metadata can be either mutable or immutable.

Copyright

Copyright and related rights waived via CC0.