This ERC defines an overlay interface and metadata schema for representing Environmental, Social, and Governance (ESG) assets with existing token standards. Compliant contracts expose ESG metadata through a token-specific URI and an optional on-chain metadata view, record attestations as cryptographic digests, and emit events when assets are minted, audited, attested, or retired. The interface is intended to be implemented alongside ERC-20, ERC-721, or ERC-1155 so that ESG assets can keep their normal transfer semantics while adding machine-readable lifecycle state.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 and RFC 8174.
This ERC is an overlay for tokenized ESG assets. Implementations maintain normal token ownership and transfer behavior through a base token standard, and add this ERC's functions for ESG metadata retrieval, audit recording, attestation recording, and retirement. Each token has a lifecycle status of issued, audited, or retired.
Tokens MUST expose a metadata JSON document with the following minimum fields. Implementations MUST make this document available from esgURI(uint256 tokenId). Implementations MAY also return the same values through getMetadata(uint256 tokenId) when storing the metadata on-chain.
The standard field identifies the metadata version. The category field describes the ESG asset class. The geo field identifies the geographic area for the asset. The carbon_value field represents the asset value for carbon assets. The digest, physical_id, attestation, and evidence fields bind the token to source records, external attestations, and supporting documentation. The status field records the lifecycle state.
Contracts implementing this standard MUST support the following interface:
This ERC does not replace ERC-20, ERC-721, or ERC-1155. A compliant contract implements this ERC in addition to at least one base token standard.
esgURI and immutable metadata.issued to audited to retired).Copyright and related rights waived via CC0.